IDE PATA, SATA, SCSI Hard Disk Drives (HDD), SSD, CD/DVD and Blu-ray drives

This section of this website consists of three long pages providing detailed information on all of the types of drives used in desktop and laptop PCs - internal and external hard disk drives (HDDs), flash-memory solid state drives (SSD drives), optical CD/DVD/Blu-ray and floppy disk drives. The Contents menu below links to the different categories of drive information. Network Attached Storage (NAS) devices are dealt with in the Networking section and USB Flash Drives are dealt with in the RAM section of this website. The very popular Hard Disk Drive Problems and CD/DVD Drive Problems sections of this website provide solutions to many common and less common problems with those drives. Taken together, you should be able to find all of the information you need to know about computer drives and their problems in the above-mentioned sections of this website.

An introduction to hard disk drives

Internal hard disk drives

Almost every modern desktop PC or laptop/notebook PC contains at least one internal hard disk drive (HDD) of the kind shown in the image above as the permanent mass storage device for its software - and/or an internal Solid State Drive (SSD) of the kind shown in the image below (make/model: Corsair Force 60GB Solid State Drive), which is a wholly electronic device (does not have the spinning disks and heads used by a hard disk drive). The new very thin and light Ultrabook laptops have an SSD drive instead of a hard disk drive, which means that due to the much higher cost of an SSD drive their data storage capacity is much less than most current standard laptops.

If performance is what you require most from a laptop or desktop PC, one equipped with an SSD boot drive is the way to go. On average, for long sustained operations, an SSD drive writes data three times faster and reads data twice as fast as the fastest standard hard disk drive. The figures for activities undertaken at peak performance are even faster.

Note well that SSD drives do not need to be defragmented, which hard disk drives require periodically, due to the fact that the data is saved to banks of flash RAM memory, not magnetic disks. Overuse of certain areas of the drive will wear it out more quickly than is necessary because the storage cells have a high but limited number of times that they can be written to. Therefore, the operating system has to know how best to use an SSD drive to minimise wear and prolong the life of the drive. Windows 7 provides the required support and is currently the best operating system to use with an SSD drive.

Read the article on this website called How to set up an SSD drive in Windows 7 optimally to increase its limited lifespan, which explains how to do that.

The installation of a 2.5-inch SSD drive (which all use the same SATA interface as a hard drive) in a desktop PC is easy if a caddy comes with the drive, allowing it to be installed in a 3.5-inch drive bay designed for 3.5-inch hard drives. Some SSD drives come with a 3.5-inch caddy (also know as a drive cage or enclosure) and some provide cloning software and external enclosures that are used to transfer the data on a hard disk drive to an SSD drive. If an SSD drive doesn't come with any of that stuff, you'll have to find your own alternatives, so, if you don't want to search for them, make sure that they come with the drive. Free cloning software is available, often from the drive manufacturer's website and elsewhere on the web.

Some laptop PCs come with a spare drive bay that allows the installation of an extra hard disk drive or SSD drive, but the installation can prove to be very problematic, as illustrated by Fred Langa in the following article.

Some ugliness installing an after-market SSD -

http://windowssecrets.com/top-story/some-ugliness-installing-an-after-market-ssd/

Note that it is now [January 2013] possible to buy a SSD in tyhe form of a PCI Express card, such as the P320h, available in 350GB and 700GB cards, made by Micron technology (aka, Crucial), priced at a huge $3,495 and $6,995 respectively. Read the following artricle for more information on these cards. -

http://www.tomshardware.co.uk/p320h-ssd-pci-express,review-32600.html

Only the cheap laptops, such as the Asus Eee laptop, designed for use in the third world make do with just flash memory, as the Apple iPhone does, to store the operating system (usually Linux) and software.

The hard disk drives and SSD drives used in most desktop and laptop PCs use the serial ATA (SATA) data-transfer standard, which has replaced the IDE ATA standard, also known as Parallel ATA (PATA). The SATA standard has reached SATA 3.0, which is required to make full use of a fast SSD drive, but an SSD drive works perfectly well from an SATA or SATA 2.0 port.

Note that SATA-to-IDE adapters are available for use with both desktop and laptop PCs that convert an SATA drive so that it can be connected to an IDE connector on the PC's motherboard. This is particularly useful with a laptop, which usually only has room for one hard drive, that has an IDE hard drive. An SATA hard drive cannot use the IDE power and data cabling unless an adapter is used. To locate vendors, use a web search query in a search engine such as: desktop/laptop sata-to-ide adapter. Since the SSD drives that can be used instead of hard drives use the SATA interface, adapters that make it possible to use one on an IDE type of connection are also available, but are currently more difficult to find, probably because the much more expensive SSDs are not being widely used yet.

The other much less used data-transfer standard is called serial SCSI (SAS), which has replaced the parallel SCSI standard (all drives now use a serial standard that transfers data in serial packets instead of along parallel lanes). SCSI/SAS is not used in home computers and so is not dealt with here in detail.

The hard disk drives for the desktop PC have a width of 3.5 inches (3.5") and those for laptop PCs mostly have a width of 2.5 inches (2.5") (or, rarely, 1.8 inches (1.8") for laptop hard disk drives). The standard width of an SSD drive is 2.5 inches (2.5"), so an adapter, usually provided with the drive, is required to install an SSD drive in a 3.5" bay of an ATX desktop-PC case.

Note well that in an SSD drive, MLC (multi-level cell memory technology) flash memory is cheaper, faster and allows for higher-capacity drives than SLC (single-level cell memory technology) flash memory. There are not many SLC SSD drives around and there probably never will be, but you should be aware of the difference between the two types in case you find and buy an SLC drive.

Intel has developed SSD caching technology that allows an SSD drive to be used in conjunction with a hard disk drive. The most commonly used files are stored on the SSD drive for ultra-fast access, boosting boot times and performance significantly. However, the computer's motherboard's chipset has to support the use of Intel's technology and most motherboard chipsets don't support it. To provide similar technology to allcomers, Crucial, the RAM memory manufacturer, has made its Adrenaline SSD drives and caching technology available for desktop PC's. To use it, just buy an Adrenaline SSD drive, which comes with a 3.5-inch caddy for installation in a 3.5-inch drive bay, install it to an SATA port on the motherboard and then install the software that comes with the drive. The caching then happens automatically.

SSD drives are currently very mush more expensive than SATA hard disk drives and have much less data storage space. For example in July 2012, an internal 1TB samsung SATA 3.0 hard drive was priced at £60, while a 1TB OCZ Octane SSD drive was priced at a huge £1963. The lower-capacity SSDs are more reasonably priced. In July 2012, a Crucial 256GB SSD was priced at around £155.

To get an idea how much hard disk and SSD drives currently cost, visit the Amazon website the serves your country. In the UK, it's amazon.co.uk and the information is found by looking under Computer & Office => Computer Components in the main site menu. It is also always worthwhile reading the purchaser reviews, which are often very informative.

For example, in August 2011 a 512GB SSD drive cost from between £500 to £1700, depending on the type. A standard internal drive could be purchased for around £500, but a 512GB SSD drive on a PCI Express expansion card, such as the OCZ Z-Drive R2 PCI-Express SSD 512 GB Internal hard drive, could be purchased for around £1700. Due to floods in Thailand in November 2011 that hit the hard-drive factories of all three of the major manufacturers, the price of hard drives soared. The extra cost was still adding about £60 to the cost of a desktop PC by January 2012, but will lessen as time passes and the manufacturing capacity gets back to normal.

In January 2012, a 2TB Seagate Barracuda Green hard drive (2000GB), still priced at a premium due to the Thailand floods, was priced at around £105, which works out at a mere £0.05 (5 pence) per gigabyte, compared to solid-state storage that currently costs at least L70 for 64GB (£1.09 per GB). A 64GB SSD drives can currently cost as much as £116, which is £1.80 per GB.)

The majority of all internal hard disk drives are produced by only three manufacturers: Toshiba, Seagate and Western Digital. There used to be six, - Hitachi, which absorbed IBM's hard-drive business, Samsung and Maxtor, but they were all absorbed by the big three.

By January 2012, hard disk drives have reached capacities of 3TB (3000GB using the method that the drive manufacturers use to determine 1TB as being 1,000GB, not the 1024GB used by software developers) and their capacities will keep increasing. Note that there are several issues with regard to using a hard disk drive as the boot drive if it has a capacity larger than 2.19TB. A hard drive with a capacity higher than that requires a 64-bit operating system (a 64-bit version of Windows, which means a 64-bit version of Windows Vista or Windows 7), device-driver support and has to be formatted to the GPT file system and have UEFI BIOS support. Note that Windows XP and later versions of Windows support GPT, but only 64-bit Windows Vista and Windows 7 & 8 support it during the boot process.

The BIOS has to be an UEFI BIOS. For example, to overcome all of these issues, Western Digital provides a HighPoint Rocket 620 adapter card that uses a PCI Express x1 slot on a motherboard with its 3GB drives, which supports booting to a formatted 3TB drive if the motherboard provides UEFI support, which most motherboards currently in use do not.

Read the following Q&A on this website for more information on this topic: Can an ultra-large-capacity 3.0TB hard disk drive be used with Windows XP, Vista or Windows 7?

The following article provides detailed information on the 2.19TB barrier.

The 2.19TB Barrier - http://www.anandtech.com/show/3981/...

Windows Vista, Windows 7 and Windows 8 fully support storage (non-boot) drives larger than 2.19TB conncted to a computer with a standard BIOS (not a UEFI BIOS).

For example, Windows Disk Management can format a 3TB external drive normally as long as the user chooses to format the drive as a GPT partition, which allows Windows Vista/Win7/Win8 to create a single partition of a drive with a capacity exceeding 2.19TB. GPT uses 64-bit addressing that allows an truly enormous partition size of 10 zettabytes (ZB) - a 1 followed by 21 zeros, measured in bytes of information. The number of bytes of information in a terrabyte (1TB) is a 1 followed by 12 zeros. Every time a zero is added the whole number is multiplied by ten, so the GPT file system is going to around for a very long time.

GUID Partition Table - http://en.wikipedia.org/wiki/GUID_Partition_Table

The Master Boot Record (MBR) format used by the FAT followed by the NTFS file systems, used for decades, has a maximum patition size of 2.19TB, therefore for partitions larger that they have to be patitioned as GPT partitions. It's a 32-bit limit that goes along with the RAM-memory limitation in 32-bit systems of 3.2GB. To use bigger partitions requires 64-bit addressing and more memory requires using a 64-bit version or Windows (Vista, Win7, Win8) or another 64-bit operating system, such as Linux.

The new format also lets you create more than four primary partitions on the same drive. MBR can only be used to create four primary partitions (defined as a partition that can be used as a bootable system partition). A primary partition can be further partitioned into one extended partition that can itself be partitioned into logical partitionsthat are each given a drive letter (G:, H:, etc.) but can only be used for data storage or have software installed on them that is not the operating system.

On Windows computers, full GPT support requires 64-bit Windows (Vista or later) and a UEFI (Universal Extensible Firmware Interface) BIOS.

The second method applies to systems with traditional BIOS and/or 32-bit Windows installed. These systems can work with primary (boot) partitions larger than 2TB, but to do so they need intermediary software (such as Seagate's DiscWizard) to handle the necessary addressing conversions.

Full GPT support requires a 64-bit version of Windows (Vista/Win7/Win8) and a UEFI - Universal Extensible Firmware Interface - BIOS. Note that from Vista to Windows 8, 32-bit and 64-bit versions are available. A 32-bit version of Windows cannot be upgraded to a 64-bit version. To have a 64-bit version requires a clean installation using a 64-bit installation DVD.

To open Disk Management, which provides the information and formatting options on the installed data-storage drives, in XP enter the diskmgmt.msc command in the Start => Run box. It's the Start => Search box in Vista/Windows 7. In Windows 8, press the Windows key (the one with a flag on it) plus the X key on the Desktop screen to bring up a menu containing it or press the Windows plus the R key to bring up the Run box and enter that command in it.

Windows XP cannot format drives exceeding 2.19TB, but if the drive is an external, non-boot drive, the drive manufacturer can provide and installation option to format it for Windows XP compatibility. The drive's user manual should explain what to do.

This article reviews four 3TB hard drives made by Hitachi, Seagate and Western Digital, providing information on why they don't always work as expected:

http://www.tomshardware.co.uk/3tb-hdd-hard-drive,review-32271.html

External hard disk drives and CD/DVD/Blu-ray writers/drives are available that are connected externally to the desktop or laptop computer using a USB or FireWire interface. They are dealt with on Page 2 and Page 3 of this article respectfully.

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The image below shows an IDE ATA hard disk drive (a type now mostly replaced by SATA hard and optical DVD/Blu-ray drives, but still being used in millions of computers) installed in a 5.25-inch drive bay of a PC case. The date of updating this information is January 2012 and IDE hard drives can still be purchased up to a capacity of 500GB. If you have a computer that can only connect IDE drives via its motherboard, you can purchase a PCI or PCI Express SATA adapter card that allows the installation of SATA drives. The black, yellow and red wires, connected to the hard disk drive's power input port by a white Molex power connector, come from the power supply unit, the bottom of which can be seen in the top left of the image. The large yellowish ribbon cable is the drive's IDE data cable, which is connected to the motherboard (the large printed circuit board attached to the back of the case) and to the drive itself.

SATA drives are connected to the motherboard in the same way but each cable can only be attached to a single drive (most IDE cables can accommodate a combination of two IDE hard-drives or CD/DVD drives in a master/slave or Cable Select configuration). Most motherboards provide 6 SATA numbered connection ports. The number determines the boot order of the drives, which means that the boot hard drive has to be installed on the lowest-numbered connection port. Not necessarily number one, but the port with a lower number than any other drives.

The image below shows two SATA hard disk drives installed in the middle bay of an Antec P180 ATX case with two optical CD/DVD/Blu-ray disc drives (one an SATA drive and the other an IDE drive) installed in the top bay. As you can see, the SATA cables are much thinner than the IDE ribbon cable shown in the image above and therefore don't impede the flow of air through the case nearly as much as ribbon cables. The power supply is installed in the bottom left area instead of the usual position in the top left area.

For your information, IDE stands for Integrated Drive Electronics and ATA stands for Advanced Technology Attachment. IDE drives are also known as PATA drives. The P stands for parallel, because the data is transferred in parallel down the 40 wires in the ribbon cable.

Note that IDE hard disk and optical disc drives have now largely been replaced by serial ATA (SATA) drives.

Serial ATA - http://en.wikipedia.org/wiki/Serial_ATA

Detailed information on the SATA standard is provided further down in this article. Click here! to go directly to it.

An IDE cable is attached to a CD/DVD drive (attachment unseen) installed in a drive bay at the top of the case, but it could also have been attached to the same cable, because a single IDE cable can accommodate two IDE drives, which can include a CD/DVD/Blu-ray drive. The cable is attached to the motherboard using the connector beside the connector to which the hard disk drive is connected.

External hard disk drives (attached from outside the case) that are attached to the desktop or laptop PC via USB (the most common interface), FireWire and eSATA (external SATA) ports, can be used for additional storage, but should not be used as the main source of disk space, even though it is possible to do so, because of problems that can occur with the device driver software. Visit Page 2 of this article for more information on them.

Some desktop PCs and laptop PCs now use a Solid State Drive (SSD) - a flash-memory drive instead of a hard disk drive, but they are currently exceptions to the rule because flash memory currently costs much more than hard-disk space, consequently SSD drives have much less drive space (32 to 512GB) compared to hard disk drives (up to 3000GB or 3TB in January 2011). If there were a 1TB (1000GB) SSD drive, which there isn't yet, it would probably cost as much as the PC or laptop itself. That said, Google is using SSD drives in its servers now because, being wholly electronic devices, they are much faster than mechanical hard disk drives.

An SSD drive uses much less power than a conventional hard drive, and it can withstand shocks (when a laptop is dropped, etc.), far better than conventional hard drives. At the time of writing (January 2012), the capacities of SSD drives have reached 512GB [around £580], although only 64GB [around £85] and 128GB [around £150] SSD drives are currently inexpensive enough to make them an affordable alternative to standard hard disk drives. In January 2012, a 256GB SSD drive was priced at around £295. 1TB (1024GB0 SSD drives exist but I couldn't find them on sale anywhere in the UK. The OCZ Technology 1TB Z-Drive P84 SSD Drive, which is an SSD on a PCI Express adapter card, was priced at £3125.00, having been reduced from £4200.00, so it's hardly surprising that no vendors want to stock them.

In the near future, as the prices of flash memory and flash-memory devices reduces compared to the prices of current means of data storage, it is likely that all PCs for home use will use flash memory instead of RAM memory, and SSD drives instead of hard disk drives.

SSD drives function in a different way than hard disk drives and their flash-memory space has a limited number of times that it can be written to, so, in order to lengthen the life of an SSD drive, the operating system has to use the space so as not to write to the same space all the time. The following free utility optimises Windows XP / Windows Vista / Windows 7 to use an SSD drive.

SSD Tweaker for Windows -

"Optimize Windows XP, Vista and 7 for SSD Drives With all the advice online for SSD hard drives it can take hours of research and fiddling to properly setup your SSD drive. Now with this little app you can Tweak Windows 2K/XP/Vista & 7 including x64 in seconds." -

http://www.elpamsoft.com/?p=SSD-Tweaker&Name=SSD%20Tweaker

Note well that a defragmentation utility should never be used on a solid-state drive because the operating system is set not to write to the same drive space all the time in order not to make some memory cells come to the end of their lives before others. Moreover, solid state drives access any location on the drive in the same time, making it unnecessary to have the memory cells for a file in consecutive order, which is what the defragmentation process achieves and which is necessary for a hard disk drive to work most efficiently.

Intel's Z68 motherboard chipset for its second-generation Socket LGA1155 Core i3, i5 and i7 processors supports Intel's Hybrid SSD technology, also called Smart Response Technology (SRT), which uses an SSD drive to cache the most frequently used files so that the operating system (Windows) can access them far more quickly than from the hard disk drive, improving performance. Alternative methods of pairing an SSD or flash memory and hard disk drive involve installing Windows on an SSD drive and the data files on a hard drive or having a small amount of flash memory (in the range of 4GB) built into the hard drive that is used to reduce the booting time (a hybrid drive).

Note well that if you want to use it, RAID must be enabled in the computer's BIOS before installing Windows otherwise Windows will have to be reinstalled. AHCI or IDE mode is usually enabled in the BIOS be default, so it must be disabled and RAID enabled. Some motherboards with the required Z68 chipset will require the BIOS to be updated if they weren't made SRT-ready.

Windows is installed on the hard disk drive and the SSD drive is left empty. Intel provides a disc containing the software and drivers. The software is installed on a RAID-enabled system and the computer is rebooted. SRT is then enabled by running the software.

A large SSD drive is not required. A 32GB model is more than up to the task. Intel itself has made available its 311 Series SSD drives that use the longer lasting but more expensive SLC flash memory instead the the cheaper MLC flash memory currently being used for most SSD drives.

The following webpages provide technical information on SSD drives:

Solid-state drive - http://en.wikipedia.org/wiki/Solid_state_drive

Crucial Solid-State Drives - SSD Buying Guide [Includes information on how to partition and format an SSD drive.] -

http://www.crucial.com/uk/support/ssd/ssd_buying_guide.aspx

SSD Performance: TRIM And Firmware Updates Tested [December 24, 2010] -

"Solid state drives can deliver exceptional performance, but they're not necessarily fire-and-forget upgrades. You'll only really get the best possible experience from them if you pay attention to details like TRIM support and available firmware updates." -

http://www.tomshardware.com/reviews/ssd-trim-firmware,2800.html

Best SSDs For The Money: March 2013 - http://www.tomshardware.co.uk/...

Most desktop PCs currently use 3.5" hard disk drives. Most laptop PCs currently use the smaller 2.5" hard disk drives especially designed for use in mobile, portable computers.

When the computer is switched off, the software and data files, etc., remain recorded on the hard disk drive's magnetic platters, and can be accessed by the operating system the next time the computer is switched on.

Most modern PC motherboards still have the capacity for at least two IDE PATA disk drives, which could be a mixture of a hard disk drives and CD/DVD drives, or Zip drives and LS120/LS-240 super floppy disk drives, which can use the IDE bus. IDE PATA is outgoing technology and soon most motherboards will not support it. The latest standard for hard disk drives and CD/DVD/Blu-ray drives is the serial ATA (SATA) standard, which all current motherboards support. A motherboard that supports SATA drives will usually only provide a single connector for IDE PATA drives that supports two drives on a single cable, but older motherboards that only support the IDE PATA standard usually provide two connectors that enable four drives to be connected (two drives per cable).

The current motherboards that support the latest SATA standard usually provide connectors for six SATA drives, which could be a mixture of SATA hard drives and SATA optical CD/DVD drives.

The operating system (DOS, Windows, Unix, Linux, OS X, etc.), and all of the application software (MS Office, Photoshop, Internet Explorer, etc.) is loaded by an installation program on a CD/DVD installation disc on to the hard drive's magnetic platters so that it can be retrieved and run by the operating system, which, of course, has to be instructed to do so by the computer's human operator via the computer's keyboard and mouse, touchpad, touchscreen, the computer's processor and its RAM memory.

The RAM (volatile memory) cannot presently hold any data permanently, because it records the the bits of data (as the ones and zeros of the binary numerical system) as electric charges that disappear when the computer is switched off.

If you want to know the technical details of how a hard disk drive works, click the following link and then use your browser's Back button to return to this page. - http://computer.howstuffworks.com/hard-disk.htm

There are only three main standards used to interface a computer to internal hard disk drives, CD/DVD drives, etc. - the SCSI/SAS SCSI and IDE ATA standards (the IDE ATA standard is also called PATA, which stands for Parallel ATA) - which have been available for many years, plus the latest standard called serial ATA, usually abbreviated to SATA, which is available in three versions - SATA 1.5 Gbit/s (the first version - SATA 1) and SATA 3.0 Gbit/s (the second version - SATA 2/SATA II) and SATA 6.0 Gbit/s (SATA 3).

Benefits of using SATA - http://www.sata-io.org/technology/why_sata.asp

SATA 3 and SATA 2 devices can run on an SATA 1 motherboard or adapter-card host controller, which is called backward compatibility. These three standards are also forward-compatible. An SATA 1 drive will run on an SATA 3 controller, etc., but a drive using the earlier standard cannot run at the faster data-transfer speeds of a later version of the standard.

SATA versions and backwards compatibility -

http://www.youtube.com/watch?v=ua685ReXFnI

Note that the full SATA 3.0 (SATA 6 Gbit/s) standard was released on May 27, 2009. Seagate says that SATA 3.0 is 100% faster than SATA 2.0 while being backward compatible with the existing SATA 2.0 standard with regard to cables, etc.

This is what used to be written on Seagate's website: "The SATA 6-Gb/s interface enables the use of the industry's newest and fastest hard drive controllers, while providing backward compatibility to legacy SATA 1.5-Gb/s or 3-Gb/s systems."

The latest internal hard disk drives, such as Seagate's Barracuda XT, support the new SATA/600 (or SATA 3.0) standard which runs at a theoretical 6Gb/s. Just remember that most theoretical speeds are far from being achieved in practice.

Serial ATA [SATA] - "The new specification can use existing SATA cables and connectors, although some OEMs are expected to upgrade host connectors for the higher speeds. Also, the new standard is backwards compatible with SATA 3 Gbit/s [SATA 2]." -

http://en.wikipedia.org/wiki/Serial_ATA

Note that Gbit/s is gigabit per second, not gigabyte per second. There are 8 bits in a byte of information, so the latter speed is eight times faster than the former. 1.5 Gbit/s is equal to 150MB/s (megabytes per second) and 3.0 Gbit/s is equal to 300MB/s. Consequently, you may also see these two SATA standards described as SATA 150 and SATA 300.

Data rate units - http://en.wikipedia.org/wiki/Data_rate_units

The IDE ATA standard is also known as Parallel ATA (PATA), because it makes use of a ribbon cable that has 40 conductors that transfer data in parallel, plus another 40 conductors that shield them from interference for PATA 66/100/133 drives. Round cables are also available for use with these drives.

The Serial ATA (SATA) standard is compatible by design with the original IDE Parallel ATA (PATA) standard. In fact, they are so similar that accessory adapters are available that allow an existing PATA hard drive to plug into a PCI SATA controller card or the SATA connectors on a motherboard.

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External hard disk drives

It is possible to buy hard disk drives (and other disk drives, such as floppy disk and CD/DVD drives) that connect to a desktop or a laptop PC externally via a USB, FireWire, or eSata connection.

Click here! to go to the information on external hard disk drives on this website.

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The faster, more expensive SCSI (Small Computer System Interface) drives and devices are often found employed in high performance PCs, but most often on non-PC platforms, such as Unix workstations and servers. The serial version of SCSI, which is that standard's answer to serial ATA (SATA), is called Serial Attached SCSI (SAS), which has replaced the parallel SCSI standard in the same way as the IDE ATA standard has been replaced by the serial ATA standard.

The second-named standard, IDE (Integrated Drive Electronics) ATA is much cheaper than SCSI and even though it has been replaced by the SATA standard is still the most used of the three standards because it has been in use for over a decade.

The third standard, serial ATA (SATA), potentially the fastest of them all, could transfer data as fast as 600MB/s now, but the current internal mechanisms of hard drives limit it to being not much faster than standard IDE ATA drives, which can only sustain about 60MB/s in practice.

This situation was expected to be overcome by the SATA 3.0 Gbit/s standard, but the drives that have become available that use it have not shown much of a performance increase over the earlier version of the standard (SATA 1.5 Gbit/s ), which, in turn didn't outperform the earlier Parallel ATA (PATA) drives.

SCSI technology had to adopt serial technology in order to keep ahead of the SATA 3.0 G/bit/s standard, which has a theoretical data transfer speed of 300MB/sec compared to the 320MB/sec of the fastest parallel Ultra320 SCSI standard.

SAS Hard Drives: 15,000 vs. 10,000 RPM [October 2007] -

"The performance differences between the Savvio drives at 10,000 RPM and their 15,000 RPM brothers are substantial. The Savvio 15k.1 shows huge performance advantages in all low-level benchmarks such as the access-time measurements or the data-transfer rates. However, these benefits come at the expense of smaller maximum storage capacities (73 GB as opposed to 146 GB with 10,000 RPM) and higher costs. The 15k drives did particularly well in our I/O benchmarks." -

http://www.tomshardware.co.uk/sas-hard-drives,review-29677.html

Click here! to go to the information on SCSI/SAS hard disk drives on Page 2 of this article.

Unfortunately, the IDE PATA standard has been given several other confusing marketing names by the different concerns involved in the manufacture of IDE devices - E-IDE - ATA - Ultra ATA - DMA - UDMA - Ultra DMA.

To add to the confusion, because serial ATA (SATA) drives are the going type, the older IDE kind that uses a parallel interface is now also called Parallel ATA or PATA. So, if you see a reference to a PATA drive, it means an IDE ATA drive, which will soon be used no more when the computers that have IDE drives die or are are taken out of use.

See further down this page for information on serial ATA (SATA) hard disk drives.

Both IDE PATA and SATA drives are usually attached directly to the motherboard by special ribbon cables.

The type of IDE PATA ribbon cable shown in the image below on the left can accommodate two drives each. There is a second connector that connects to a drive in the middle of the cable.

Note that most IDE PATA data cables are keyed so they can only be connected to the motherboard or to the drive itself in the correct way, but some are not, making it possible to insert the connector in backwards. If that happens, the drive simply won't work.

The ribbon cable shown in the image on the right is for a floppy disk drive (FDD). It has a twist in the conductors that is clearly visible at the end of the connector that must always be fitted to the floppy disk drive itself (not to the motherboard FDD connector). Internal floppy disk drives are no longer being provided with PCs, but there are still many of them still working that have one installed, so I have kept this information here.

Inexpensive add-on PCI and PCI Express adapter cards can be purchased for an IDE PATA drive if you want to install more than the usual maximum of four drives - or if you want to use a higher mode of the standard not supported by the motherboard - or you want to use an IDE drive on a computer that only supports SATA drives. Web-search query: ide pci express adapter cards.

SATA drives use thinner ribbon cables that can only accommodate a single drive. Look further down this page to see an image that compares the two types of ribbon cable.

IDE PATA hard drives require to be connected to the power supply unit by one of its standard four-pin Molex power cables. Some older SATA hard drives can use a Molex connector, but more recent models can require to be connected to the power supply unit by the newer SATA power connector, which is thinner than a Molex plug. However, if an older power supply unit doesn't have an SATA power connector, a converter cable can be purchased from a vendor such as maplin.co.uk. It plugs into a Molex plug. Another good UK cable website that provides these cables is scan.co.uk.

Note well that some new SATA drives require a +3.3V connection that old-style ATX 1.3 power supply units can't supply; they require to be connected to a new-style ATX12V 2.0 power supply unit. The user manual for a particular make and model of drive that can be obtained from its manufacturer's site should provide information on its power requirements.

Further, illustrated information on SATA hard disk drives is provided further down this page.

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Never open a hard disk drive

Note that the Western Digital hard disk drive depicted above is shown with its top cover removed. You should never open a hard disk drive, because dust can irreparably damage or destroy it. These drives are assembled in a dust-free environment.

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What to look for in an Internal IDE/SATA/SCSI/SAS hard disk drive

Here is how the specifications for some internal (installed inside the PC case) IDE/SATA/SCSI/SAS hard disk drives as they would appear in an informative advertisement. Note that by January 2012 the capacities of both internal and external hard drives had reached 3TB (3,000GB. Drive manufacturers use the decimal 1,000GB = 1TB; software developers use 1024GB = 1TB, which is based in the binary number system, that consists only of 1 and 0, used by computers.) The 2.19TB barrier problem was covered at the top of this page.

Manufacturer	Model	Capacity	RPM	Cache	Seek Time	Interface
Western Digital	Caviar	120GB	7,200	2MB	8.5 ms	ATA Ultra 100
Hitachi	Deskstar 7K250	250GB	7,200	8MB	8.5 ms	ATA Ultra 133
Samsung	SpinPoint SP1614C	160GB	7,200	8MB	8.9 ms	SATA 150/SATA 1.5 Gbit/s
Seagate	Barracuda 7200.8	400GB	7,200	8MB	8.0 ms	SATA 150/SATA 1.5 Gbit/s
Samsung	SpinPoint SP2504C	250GB	7,200	8MB	8.9 ms	SATA 300/SATA 3.0 Gbit/s
Hitachi	Deskstar T7K250	250GB	7,200	16MB	8.5 ms	SATA 300/SATA 3.0 Gbit/s
Hitachi	Deskstar 7K80	500GB	7,200	8MB	8.5 ms	SATA 300/SATA 3.0 Gbit/s
Hitachi	Deskstar 7K1000	1,000GB/1TB	7,200	32MB	8.5 ms	SATA 300/SATA 3.0 Gbit/s
Seagate	Barracuda 7200.10	750GB	7,200	8MB or 16MB	N/A ms avg	SATA or Ultra ATA/100
Seagate	Barracuda ES.2	500GB	7,200 rpm	16MB	8.5 ms	Serial Attached SCSI (SAS)
Seagate	Cheetah 15K.4	146GB	15,000	-	3.5 ms avg	Serial Attached SCSI (SAS)
Seagate	Cheetah 73LP	73GB	10,000	4MB	5.0 ms	SCSI Ultra 160
Hitachi	Ultrastar	146GB	10,000	8MB	4.7 ms	SCSI U320 68Pin
Seagate	Barracuda ES.2	1000GB/1TB	7200	32MB	8.5 ms	SATA 300/SATA 3.0 Gbit/s
Seagate	Barracuda	3000GB/3TB	7200	64MB	8.5 ms	SATA 300/SATA 3.0 Gbit/s

MB stands for megabytes, which is approximately 1,000 kilobytes (KB). With regard to hard disk drives, only their data cache is measured in MB.

GB stands for gigabytes (1GB is approximately 1,000MB), which is a measure of the data capacity of a hard disk drive, DVD discs, or RAM and flash memory. The drive manufacturers use the decimal 1GB = 1,000MB and software developers use the binary 1GB = 1024MB. All current hard disk drives have their capacities measured in gigabytes.

TB stands for terabytes, which is approximately a 1,000GB. The drive manufacturers use the decimal 1TB = 1,000GB and software developers use the binary 1TB = 1024GB. The Seagate Barracuda hard drive listed in the table above has a capacity of 3TB. 4TB internal hard drives are available. DVD discs currently have their capacity measured in GB. RAM and flash memory is currently measured in MB and GB. The first 3TB hard drive made by by Western Digital (WD Caviar Green) was made available in October 2010.

RPM stands for the number of revolutions per minute that a magnetic platter inside a particular drive spins at.

SATA stands for serial ATA - a drive that uses a serial ATA interface, the original version of which is SATA 1.5 Gbit/s. The latest version of the standard is SATA 3.0 Gbit/s.

SAS stands for Serial Attached SCSI, which is serial SCSI. SCSI and SAS drives are not often used in home computers.

Warranty. - You are advised to check for the warranty provided with a new hard drive, as this can be for one, three, or five years, depending on the drive. External hard drives tend to have a shorter warranty than internal hard drives because they are more prone to being damaged. The manufacturer's website will provide that information if it is not provided elsewhere. You might have to use the site's search facility to find it.

The 300GB DiamondMax Plus drive shown above has only 2MB of cache, a slow access time of 12.6ms, and runs at only 5,400RPM because it is designed primarily for its storage capacity for use on systems that do not require high performance accesses. Consequently, it stays cool and will probably last longer than a drive running at 7,200RPM or 10,000RPM.

Note that an SAS or SCSI drive of the same capacity as an IDE or SATA drive costs far more than the IDE/SATA drive, as can be seen on this page with the drives arranged in order of price:

http://www.directron.com/hard-drives.html

In January 2012, the SAS and SCSI drives made available there had a maximum capacity of 80GB, which is miniscule compared to IDE drives (up to 500GB) and SATA drives (up to 3TB).

In order to stay in the game, SCSI technology has had to become serial technology called Serial- attached SCSI (SAS) - transferring data one bit at a time over thin cables. But it looks to have lost the game since even 512GB SSD drives are now available. Who would want a very expensive 80GB hard drive?

Hard disk drives use algorithms to store re-usable data in a cache made of RAM memory in order to increase performance. IDE/SATA drives have reached a cache size of 16MB/32MB respectively, and SAS drives a cache size of 16MB.

Hybrid hard disk drives use flash memory as the buffer/cache. Seagate launched the first hybrid drives with 256MB of flash memory in June 2006.

In July 2007, when the article linked to below was written, such drives were still hard to come by. In August 2008, they were still not available from the major retail suppliers in the UK.

Hybrid technology didn't take off due to reliability problems and lack of performance, but Seagate has brought out a new range of hybrid drives aimed at reviving the technology.

October 20, 2010 - Hybrid hard drives finally come of age -

http://windowssecrets.com/top-story/...

To find out what the availability of drives is in the UK visit dabs.com and look under Storage.

Visit newegg.com in the USA.

As you can see from the table above, it is now possible to obtain non-hybrid IDE and SATA drives with 16MB or 32MB of cache (16384KB/32768KB). SCSI drives are available with 8MB of cache. - The cache size is increasing as drive capacity is increasing remorselessly.

IDE/SATA hard drives usually have a revs-per-minute (RPM) rate of 7,200RPM or 10,000RPM, an SCSI hard drive, 10,000RPM, and an SAS hard drive, 10,000RPM or 15,000RPM.

Note well that hard drives with a high revs-per-minute rating (7200RPM+) get much hotter than drives with a lower rating (5400RPM). Therefore, be sure to install a drive with a high rev rating in its bay so that it has space around it. Do not cram it in between other drives. If you have odd problems with the system, consider buying and installing a cooling unit for such a drive. If you don't require fast drive access speeds, if you can find one, buy a drive with a 5400RPM rating. They are less expensive, and may well last longer.

The following article provides more information on the specifications of hard drives. It is over five years old, but the information is still valid.

Understanding Hard Drive Performance : A Guide To Hard Drive Selection [March 2007] -

http://www.tomshardware.com/reviews/understanding-hard-drive-performance,1557.html

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IDE ATA drive cables

The following information deals with IDE hard drives, so there is no need to read it if your computer uses SATA drives unless you are interested in knowing about the IDE standard.

There are two types of IDE data ribbon cable. The earlier type of cable is used on PATA hard disk drives running ATA (UDMA) 33 and earlier ATA modes. This cable has 40 conductors in the ribbon. But HDDs using the ATA (UDMA) 66/100/133 modes of operation require the new cables that have 80 conductors in the ribbon, 40 of which are used to shield the others from electromagnetic interference.

In fairly recent PCs, the connectors for the drives on an IDE cable are "keyed," which means that they are designed so that they can only fit into the sockets on the motherboard (or adapter card) in the correct way. If you try to plug a cable's connector in the wrong way, it won't fit.

For more information on IDE cables visit these two pages:

Standard (40-Conductor) IDE/ATA Cables -

http://www.pcguide.com/ref/hdd/if/ide/conf_Cable.htm

Ultra DMA (80-Conductor) IDE/ATA Cables -

http://www.pcguide.com/ref/hdd/if/ide/confCable80-c.html

Visit this article on how the Cable Select (CS) feature is used to configure IDE drives - http://www.pcguide.com/ref/hdd/if/ide/conf_CS.htm. When CS is enabled the drive is configured as a master or slave drive by the position it occupies on the ribbon cable that can accommodate two drives.

Round IDE hard-drive cables

If you have a PC with one or more IDE PATA hard drive, or you are building a PC with IDE hard drive(s), you can purchase round IDE cables to replace the standard 80-pin ribbon cable(s). These can be used on any IDE PATA hard drive. Since round cables don't occupy as much space, they aid the cooling of the case, and, being easier to cover, they are more robust and hence less prone to be damaged. Single-drive cables that can accommodate a single drive instead of two drives are also available.

The cables for SATA 1.5 Gbit/s and SATA 3.0 Gbit/s hard drives are so thin that it is not necessary to make them round. Only one cable is used for each SATA drive.

The image below shows the individual cables that can accommodate two IDE PATA drives. For some reason, they come in a wide variety of garish colours, such as in blue and red.

Problems with the new round IDE cables

Anonymous post from the alt.comp.hardware.pc-homebuilt newsgroup

"Hi, I recently bought a set of CoolerMaster round IDE cables and I'm wondering if anyone has the same experience of the 45cm ones that I have. Trying to fit them on two drives close together is almost impossible without great force which didn't seem right to me. I spaced the drives apart and then only after cutting back some of the rubber shield would they bend enough to fit on the drives, if I had the drives right next to each other they just wont bend enough. The 60cm [cable] I bought for the DVD and CD burner doesn't have this problem. Also I managed to pull two of the tabs off when I needed to swap drives around. I certainly won't be buying anymore CoolerMaster cables in a hurry. I was going to buy the cheaper ones but decided on these as I thought they would be better, wish I'd have saved a few quid now."

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How to install IDE (PATA) and SATA hard disk drives: Connecting the drives to the motherboard and the power supply unit (PSU)

Installing a hard disk drive in a desktop PC is not a very complicated business, especially SATA drives that each have their own data cable compared to the master/slave setup of two IDE drives connected to a single ribbon cable.

Click here! to go directly to the Build Your Own PC page on this site that deals with installing disk drives in detail.

Here are two videos on installing IDE and SATA hard disk drives:

How to Install Internal Hard Drives : How to Connect Serial ATA Hard Drives -

http://www.youtube.com/watch?gl=GB&hl=en-GB&v=kCgFYNLzn18

How to Install Internal Hard Drives : How to Install an IDE Hard Drive -

http://www.youtube.com/watch?gl=GB&hl=en-GB&v=OMTOgt3UiB4

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Serial ATA (SATA) hard disk and SSD drives

A new type of ATA hard disk drive called serial ATA (SATA) that uses serial data transfers in packets (IDE drives use parallel data transfers down 40 wires in a cable) is now the latest type of drive. Instead of an 40-conductor and 80-conductor ribbon, or rounded IDE cable (see the section below this one for information on round cables), a serial ATA (SATA) drive's cable only has seven conductors. The image directly below shows the difference between an 80-conductor IDE ATA ribbon cable (blue) and a SATA cable (red). The considerable reduction will help with the air circulation in the computer's case.

Note that not all SATA cables are equal. The push-fit type (the red cable shown above) is just connected to the SATA connector on the motherboard by pushing it on. Unlike the wide 40-pin PATA connector, this type of cable can easily become disconnected; with enough vibration it can easily work loose and cause problems that are usually very difficult to diagnose if you don't check the cable to begin with. See further down this page for images of the type of cable that has a locking mechanism that locks it to the motherboard and SATA drive, which is much the better type to use.

IDE PATA hard drives and optical CD/DVD drives are still available (information updated - January, 2012), but all of the optical CD/DVD/Blu-ray drives provided in new desktop and laptop PC use the SATA interface now.

Installing an solid-state SSD drive is almost as simple as installing an SATA hard disk drive except that the standard format is a width of 2.5 inches (the same as a laptop hard-drive), so the drive won't fit in a 3.5 inch bay in an ATX case without an adapter. Most SSD drives come with an adapter kit that make this easy, but, if not, you wll have to buy an adapter. Also usually provided is cloning software and an external enclosure that is used to transfer data from an existing hard drive to the SSD drive.

Note that the extra 40 conductors in an 80-conductor IDE cable (compared to its predecessor, the 40-conductor IDE cable) are only used as protection against electromagnetic radiation that can interfere with data transfers. The 80-conductor cables have to be used with drives running in IDE ATA 66 and higher modes of operation. The 40-conductor cable is used with IDE ATA 33 and lower IDE drives.

A conventional ATA IDE drive uses 40 wires for parallel transmission. The wide ribbon cable and plugs are cumbersome and there are also a number of electrical limitations. Because the ribbon cables are cheaper than the round cables that are available, motherboard manufacturers tend to supply only the ribbon cables with their motherboards. Moreover, since the arrival of the SATA standard, most motherboards only have a single IDE connector and provide only a single cable, which is usually a ribbon cable.

SATA cables are compact and very easy to connect. Moreover, the connection limitations of parallel ATA (PATA), with its system of master and slave drives and up to two drives per cable, is not longer applied to SATA drives.

SATA uses a single cable per drive. You cannot attach more than one drive to a cable. Most motherboards provide 6 SATA connection ports that are numbered from 1 to 6. The boot order is determined by the number of the port, with the drive occupying the lowest number being the boot drive. The boot drive doesn't have to be attached to the first (number 1) SATA port , but no other drive must occupy a port with a lower number. While it is no longer necessary to configure the drive using jumpers, there may be a jumper setting that can reduce the capacity of the drive for motherboards that only support a certain size of drive. The image below shows cables used to connect an SATA hard disk drive to the motherboard. Note that none of theses cable has a latch connector that clips it to the motherboard connector. See further down this page for images of an Akasa SATA cable that has a latch connector.

The installation is simplicity itself - just attach the keyed serial cable to the drive and the motherboard, and attach an SATA power connector from the computer's power-supply unit to the drive. A standard four-pin Molex cable from the power supply can be converted to an SATA power cable with a cheap converter cable. The cable is keyed so that one end can only connect to the motherboard and the other end to the drive, so it can't be install the wrong way round. The image below shows the connection points on a motherboard for four SATA hard drives.

Note that there are no outer walls on these connectors that keep cables (made by the motherboard manufacturer) with a locking clip connected to the motherboard. Standard push-on cables will be supplied with the motherboard. However, you can buy SATA cables with a clipping mechanism that can be connected to the motherboard connectors shown above.

The cables for SATA drives are usually quite stiff and the standard connectors don't have any locking facility, so they can become loose and cause intermittent connection problems, such as having Windows XP/Vista/Windows 7 failing to recognise a drive.

Note that some hard drive manufacturers, such as Western Digital, use a proprietary SATA cable that locks to the drive. Western Digital calls its SATA cable SecureConnect. The end of the cable that connects to the drive has a special secure connector. The drive's user manual, obtained from its manufacturer's website, should provide an illustration of the connector.

Many motherboard manufacturers, such as Gigabyte, provide a locking mechanism on the motherboard connector that a locking clip on the cable fits over. All motherboard manufacturers provide SATA cables for their motherboards. SATA cables made by Akasa, such as the Akasa SATA-II 45cm Silver Data Cable, have a locking clip. Here is a review of the cable by a purchaser: "The designers that designed the original SATA data cables without any form of retention were idiots. Didn't they learn from the IDE cable design that started out without a latch but was soon given one. Replace the basic red push-on cables with these - especially if the PC gets moved around a lot." Akasa also make right angle SATA cable with a latch that has the connector at a right angle to the cable, making installation easier.

To see an image of a right-angle cable search for right angle sata cable. When searching for products in a search engine, note that the top links are usually Google/Bing ads not search links. I say this because I think that disguising ads as search links is dishonest money-making trickery. Google's search is now dominated by its own ads and Google Shopping. When you see Shopping results... showing images of the products, that is the Google Products price-comparison site, which is the only price-comparison site allowed to use images in Google's search engine. More cheating.

The image on the left shows the cable and the image on the right shows a close-up of the locking mechanism on the cable. This kind of cable can connect to an SATA connector on the motherboard of the type in the image shown above. It just pegs the cable to the connector.

If the motherboard has a mixture of IDE PATA and SATA drive connectors (ports), and you want to install both types of drive, consult the motherboard's manual to find out how to install a particular type of drive (IDE or SATA) as the primary drive and as secondary drives.

Note that it can be tricky connecting both IDE drives and SATA drives to the motherboard. If, say, you install a SATA drive and then install an IDE drive, unless the BIOS is programmed to know the difference, the system will usually try to boot from an IDE or an SATA drive first, depending on hoe old its is.

If a BIOS update isn't available that allows the two types of drive on the motherboard to be installed so that the system can boot from the SATA drive, you'll have to buy a PCI SATA adapter card and set the BIOS as instructed in this Q&A: A problem with an old IDE hard drive and a new SATA drive running from a PCI SATA adapter card.

If you are just connecting one or more SATA drives, each drive can be connected to each of the SATA connection points on the motherboard, or on a PCI SATA adapter card, because each drive has its own cable and is independently controlled by the SATA controller.

As with other serial standards such as USB and FireWire, SATA drives can be hotplugged and hot-unplugged. In other words, you should be able to connect and disconnect a drive while the computer is running. However, note well that inadequate support on the part of the manufacturer of the controller, or the hard disk drive itself may make implementing this feature problematic, so it's always best to switch the PC off before installing and removing an SATA drive.

As is the case with standard parallel IDE PATA drives, PCI and PCI Express adapter cards for serial ATA (SATA) drives (that are installed in the available PCI and PCI Express slots on the motherboard) are available. The most well-known manufacturer of such adapter cards is promise.com.

If a time comes when a standard IDE PATA controller is not available on a new motherboard and you want to use its serial ATA port for a parallel IDE drive, you can use a special adapter to connect it to the serial ATA (SATA) controller. You connect the ribbon cable to an IDE connection point on the adapter, and then connect the adapter to the motherboard with a serial ATA (SATA) cable. Such an adapter, such as the RocketHead 100, is manufactured by HighPoint Technologies Inc.

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Windows XP: Installing the device drivers for a boot SATA drive

SATA hard disk drives have only become available fairly recently. By 2008, SATA had 99% of the hard-disk-drive market, but there are still many millions of desktop and laptop computers in use running IDE drives. SATA drives were made available long after Windows 98, Windows 2000 and Windows XP were released, so they don't have the drivers for them. If you are installing an SATA drive on a system that already boots from an IDE ATA hard drive, you can obtain the driver file and point Windows to the file's location in a folder or on a CD/DVD when Windows asks for it on the first boot after such a drive has been installed. But if you're installing a bare SATA drive on a new motherboard on a PC that does not have Windows XP installed, then you have to do the following:

1. - Read the motherboard's manual, which can be downloaded from the motherboard's site if you don't have one. There will probably be a jumper that has to be enabled before the SATA controller can be used. The manual will tell you where to find the jumper on the motherboard and how to enable it.

2. - Download the SATA driver file from the motherboard's site.

3. - Copy the driver file to a floppy disk. If your computer doesn't have a floppy disk drive, a workaround is provided below. With the SATA drive mounted in the case, connect the keyed SATA cable to the drive and the motherboard, connect a power cable from the power supply unit (PSU) to the back of the drive, and set the boot order in the BIOS to boot from CD-ROM first, follwed by the SATA option. In elderly systems, the SCSI option could be used for SATA hard drives. The motherboard's manual can tell you what the boot order setting has to be.

Install Windows XP from its installation CD (the BIOS must have the CD/DVD drive set as the first boot device). Windows will detect the new hard drive. Press the F6 key when Windows asks you to do so, and then allow Windows to install the SATA drivers from the floppy disk. You can now install Windows, which will allow you to partition/format the drive/drive partitions as required.

If you have a laptop or desktop PC that does not have a floppy disk drive, read the following article that provides a workaround.

Install Windows XP on SATA without a Floppy (F6) -

http://news.softpedia.com/news/Install-Windows-XP-On-SATA...

If a desktop or laptop computer running Windows XP/Vista/Windows 7 doesn't have a floppy disk drive, you can create a slipstreamed installation CD/DVD disc that contains all of the available service packs and any drivers that are not installed, such as SATA and RAID drivers in Windows XP.

There is plenty of information and tutorials on slipsteaming Windows XP/Vista/Win7 on the web . (At the time of writing this, the first Service Pack - SP1 - for Windows 7 had been released, making it possible to create a slipstreamed disc. (By October 2012, there was no SP2 for Windows 7, but it was expected to be released soon.)

If you are creating a slipsteamed Windows XP installation disc and you want to add the SATA drivers to it so that they are installed when Windows XP itself is installed or reinstalled without having to press the F6 key when asked to and install them from a floppy disk, note well that you have to add the 'Text Mode' drivers, because the Plug and Play (PnP) drivers that are installed on an existing installation of Windows XP at startup won't work.

Visit this article: Making and Customizing an Unattended Windows Install CD. It tells you how to obtain the correct drivers.

Windows Vista and Windows 7: Installing the device drivers for a boot SATA drive

Unlike with Windows XP, which requires a floppy disk containing the SATA device drivers to be used at system startup, if the BIOS setup program recognises an SATA hard disk drive as the boot drive, Windows Vista and Windows 7 should be able to install its device drivers during its setup installation procedure. If Vista or Win7 asks for the drivers, it allows the user to search through all of a computer's storage devices for them, including a USB flash drive, not just the floppy disk drive, as is the case with Windows XP.

Hard disk drive problems - SATA hard drives

There are several Q&As that discuss installation and other problems to do with SATA hard drives on the Hard Disk Drive Problems pages on this site. Look on Page 1, Page 2, and Page 3.

For example, How can I restore Windows XP to a serial ATA (SATA) hard disk drive?

Here is another Q&A worth reading, because it deals with the SATA and RAID settings in the BIOS setup program:

If I connect an SATA hard drive to my PC, it won't boot. It gives error message "hal.dll is corrupted"

SATA device drivers for Windows 98 or Windows Me

This is advice I found with regard to an SATA drive in the motherboard manual for an AMD Socket 939 motherboard from MSI that runs Athlon 64 and 64 FX processors:

"MSI Reminds You... 1. Please note that users cannot install OS, either WinME or Win98, in their SATA hard drives. Under these two OSs, SATA can only be used as an ordinary storage device..."

This means that SATA drivers that can be transferred to a floppy disk, as described above for Windows XP, are not available for Windows 98 and Me. However, the boot IDE ATA hard disk drive will be able to access the SATA drive and allow files to be transferred to and from it, etc.

In short, in order to use an SATA hard drive in a PC running Windows 98 or Windows Me, the motherboard manufacturer must make the drivers for those versions of Windows available. If it doesn't you can't run those versions of Windows from an SATA drive.

If the motherboard manufacturer provides the drivers, and you are still having trouble using an SATA drive, you can find information of your own by entering a search, such as windows 98 sata support , in a web search engine.

SATA 1.5 Gbit/s and SATA 3.0 Gbit/s hard disk drives

There are now two different versions of SATA. The original standard, also known as SATA 1.5 Gbit/s (1.5 gigabits pers second), supports a theoretical maximum data transfer speed of 150MB/s. SATA 3GB/s (3 gigabits pers second), supports a maximum data transfer speed of 300MB/s, which equals 3GBits/s.

At present, the SATA 1.5 Gbit/s standard only provides a slight increase in performance over the earlier IDE ATA standard. The full performance benefit of having SATA was supposed to arrive with new SATA 3.0 Gbit/s hard disk drives and motherboards, which became available in 2005. The theoretical data transfer rate is supposed to be double the rate of the original SATA 1.5 Gbit/s standard (3GB/s compared to 1.5GB/s), and there are other technological improvements, such as intelligent data access queuing that minimises the time required to find data on the SATA 1.5 Gbit/s drive's disk platter.

However, the faster interface has still had little impact on drive performance, apparently because the mechanics of the drives are still not fast enough to make use of the extra bandwidth that the new standard can deliver.

Note that SATA 3.0 Gbit/s drives can be connected to a SATA 1.5 Gbit/s connector on a motherboard, and vice versa, but an SATA 3.0 Gbit/s drive connected to a SATA 1.5 Gbit/s socket will run at the rate of a SATA 1.5 Gbit/s drive. Not that it will make much difference, because there is next to no difference between the two versions.

However, note that some SATA 3.0 Gbit/s drives, such as those made by Samsung, still have to be set manually to SATA 1.5 Gbit/s (SATA 150) mode by using a small jumper on the back of the drive before they can be connected to an SATA 1.5 Gbit/s socket on a motherboard. Whether or not this has to be done depends on the motherboard, so check in its user manual to make sure. If you don't have a user manual for your brand-name PC or a PC's motherboard, download a copy from its manufacturer's site.

CD/DVD drives and SATA

There was a time when, although SATA CD/DVD drives were available, most CD/DVD drives still used the standard parallel IDE ATA interface. CD/DVD drives, being much slower to access, didn't require a faster standard than IDE ATA, but now most hard disk and CD/DVD/Blu-ray drives are SATA drives.

Power supply units that support SATA drives

Power connectors for SATA hard disk drives are available on all new ATX12V 2.0 power supply units, so no adapter cable is needed to power them. However, you have to use an adapter if you have an old ATX 1.3 power supply, which does not provide SATA power connectors, or the SATA hard drive itself does not have a standard four-pin ATX 1.3 power connector. See the image of two SATA adapter cables below. The white four-pin Molex (LP4) connector fits into a power-cable connector from the standard ATX power supply unit and the black plug fits into the SATA hard disk drive (or the optical SATA CD/DVD drives that have replaced IDE drives). Note that some recent ATX12V 2.0 power supply units may not provide you with sufficient SATA power connectors for your SATA drives, but will no doubt provide many Molex connectors, so before you buy a power supply make sure that it provides the number of SATA power connectors that you require or you will have to buy adapter cables.

You can also buy a splitter cable that provides two SATA power connectors, as shown in the image below, which shows the Molex plug (M) and the SATA plug (x 2).

Most new SATA drives don't provide a standard Molex power connector, only an SATA power connector. However, a conversion cable will always be available so that an old-style ATX 1.3 power supply unit can be used with an SATA hard drive. If a power supply unit doesn't provide an SATA power connector, a Molex-to-SATA converter cable can be purchased for about £1.20 from a vendor such as amazon.co.uk.

Note that an old-style ATX 1.3 power supply does not provide a +3.3V connection via a Molex cable, but some new SATA hard disk drives require this voltage. If so, only one of the new ATX12V 2.0 power supply units can provide it. If you have such a drive and an old-style power supply, you will have to buy a new power supply. You can download the user manual for any make and model of hard drive from its manufacturer's site. It will provide you with the power requirements of a particular model. ATX12V 2.0 is the new power supply standard that has replaced the ATX 1.3 standard. The 3.3V SATA connector, shown in the image below, is available in straight and right-angled versions, and comes directly from the ATX12V 2.0 power supply unit so that a conversion cable of the kind shown above is not used. As mentioned earlier, a right-angled cable has its connector at a right angle to the cable

Click here!to go to more information on the new ATX12V 2.0 power-supply standard on the second of the three Motherboard Cases and Power Supplies section this website. Use your browser's Back button to return to this point on this page.

SATA data cables

SATA 1.5 Gbit/s, SATA 3.0 Gbit/s, and SAS all use the same data cables, so if you see a data cable labelled as a SATA 3.0 Gbit/s (SATA 300) cable, you can use it with an SATA 1.5 Gbit/s (SATA 150) drive and vice versa. An SATA 300 cable might have a redesigned plug on the end to prevent it from coming off the drive. If you already have the SATA 150 cable, and want to reuse it for a SATA 300 drive, it will work.

Remember that the difference between SATA 150 and SATA 300 is the bandwidth of the serial interface (the amount of data that can be transferred during a second, not the speed of the drive. The latest SATA 300 hard drives are barely reaching the limits of the IDE ATA 100 standard, and can't come close to filling the bandwidth available for SATA 150/SATA 300. Therefore, it's a waste of money buying a SATA 300 hard drive, because a similar model SATA 150 drive should be just as fast.

SATA II (SATA 300) is a marketing ploy. In fact, the SATA-IO board says that there are no SATA II devices and that the term SATA II should never be used to describe a product.  It would be a similar situation to building a road where the posted speed limit is 700 MPH, but the existing cars can't go over 275 MPH. Who cares if the SATA 300 bandwidth is 3.0Gbps if the drives can't even use the full IDE ATA 100 bandwidth?

Serial ATA - http://en.wikipedia.org/wiki/Serial_ATA

Data rate units - http://en.wikipedia.org/wiki/Data_rate_units

Serial ATA: a site devoted to the new SATA drive standard -

http://www.serialata.org/

Serial ATA Adapters and Cables [a US site] - http://www.xoxide.com/seataad.html

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Hard disk drive diagnostic and maintenance tools/utilities and tests

Note well that it is always sensible to make a backup of a hard disk drive that you suspect is failing (if you value its contents) before you run diagnostic tests, because the extra stress of the testing could kill the drive.

How to run CHKDSK in Windows XP, Windows Vista and Windows 7

In Windows XP, open My Computer, right-click on the C: drive (or any other drive you want to check), and select Properties => Tools. Click Check Now under Error-checking. A Check Disk box opens. Select the Automatically fix file system errors option and the Scan for and attempt recovery of bad sectors if you have to or want to run that very long test. Otherwise leave that box unchecked. You click the dialog box's own Start button to run the disk-check tests.

A dialog box warning you that Windows can't complete the tests until you reboot enquires if you want to postpone the test until that time. It says: "The disk check could not be performed because the disk check utility [chkdsk] needs exclusive access to some Windows files on the disk. These files can be accessed only by restarting Windows. Do you want to schedule the disk check to occur the next time you restart your computer." Click the Yes option and then repeat this process for any other hard disk drives or partitions in the system. You can then reboot when all the drives/partitions have been scheduled for a disk check when Windows restarts. Windows then checks each drive or partition to whatever level of thoroughness you selected, and repairs any correctable errors.

In Windows Vista and Windows 7, click Start => Computer => right-click the drive that you want to check, and then in the menu that comes up click Properties => Tools => Error-checking.

Click here! to go directly to more information on chkdsk on the Recovering Windows XP page on this site. Use your browser's Back button to return here.

Read the section below to find out how to run the checks by using the chkdsk command from the command prompt.

ScanDisk in Windows 95/98/Me

In Windows 95/98/Me, run ScanDisk (under Start => Programs => Accessories => System Tools). You have a choice of the type of test to run. Select the Thorough test if you have problems with the drive that the Standard test doesn't fix with the Automatically fix errors box checked. The Thorough option can take a half an hour or more to run, depending on the size of the drive or partition. Windows should complete the tests without the need to reboot. Repeat this process for any other hard disk drives or partitions. If you can't run the Thorough tests from Windows, you can run the same tests from MS DOS in Windows 98. Restart the computer , press the F8 key after the system beep, and run the Command Prompt Only option. At the C:\> prompt enter the command ScanDisk /all /autofix /surface to to run the Thorough check and repair all the drives in the system. Omitting the /surface switch in the command runs a faster but less thorough check.

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Third-party hard-disk-drive (HDD) diagnostic utilities and tools

MHDD is the most popular freeware program for low-level hard-disk-drive diagnostics. -

http://hddguru.com/software/2005.10.02-MHDD/

You can find many other free hard-disk-drive utilities at http://hddguru.com/.

Diagnostic utilities provided by hard disk drive manufacturers

Most of the HDD manufacturers (Seagate, Maxtor, Western Digital, etc.) provide a diagnostic utility that can be used to diagnose problems with their drives from their websites. These utilities might also be able to partition and format a hard disk drive, which is a godsend if you're using Windows 95/98/Me with a drive(s) larger than 64GB, because the DOS FDISK utility has problems with drives of that size and larger - even if you're using the updated version. Click here! to read more about FDISK on the next page of this article. Use your browser's Back button to return here.

Where to download the hard-disk-drive diagnostic utilities for a particular make of hard drive

Where to download the hard-disk-drive diagnostic utilities for a particular major make of hard drive

MHDD is the most popular freeware program for low-level hard-disk-drive diagnostics. -

http://hddguru.com/software/2005.10.02-MHDD/

Seagate - SeaTools -

http://www.seagate.com/support/downloads/seatools/

Note that Maxtor and Quantum hard drives use SeaTools (above).

Western Digital - Data Lifeguard - http://support.wdc.com/download/

Hitachi/IBM - Drive Fitness Test -

http://www.hgst.com/support/downloads/

Here is a computer-form thread that discusses what to do when Chkdsk reports bad sectors on a hard drive and SeaTools, Seagate's hard-drive diagnostic tool, gives the drive a clean bill of health.

CHKDSK vs Seagate diagnostic tools -

http://windowssecrets.com/forums/showthread.php/...

If one of the links doesn't work, enter the manufacturer's name in a search engine if you don't know its website address and look for the utilities it provides.

Note well that if such a utility is used on a faulty system (suffering from bad RAM, an inadequate power supply unit, a faulty motherboard, etc.) it could produce unreliable results.

See the next section on this page for information on the SMART (S.M.A.R.T.) diagnostic program.

Note that it is possible for a HDD to be faulty yet pass all of the tests conducted by one or more diagnostic utilities. I have come across a case in which a Windows XP system kept failing within a short time of being restored to a previous state by restoring a master image, applying a Restore Point, or by using XP Pro's ASR (Automatic System Recovery) facility. Western Digital's diagnostic utility gave the drive a clean bill of health. But the problem was only solved by replacing the HDD and restoring a master image of the system to it. The system then functioned flawlessly, but began failing as soon as I installed the previous drive as the boot drive. I then installed the faulty drive as a slave back-up drive, and it worked properly in this role. Therefore, don't rule out the HDD as being the source of system failure just because diagnostic utilities give it a clean bill of health.

Hard Drive Diagnostics - the MS Knowledge Base

The following MS Knowledge Base (KB) article deals with an IDE/ATAPI drive problem that can afflict Windows 2000 and Windows XP systems. Click the article's number to go to it.

817472

IDE ATA and ATAPI Disks Use PIO Mode After Multiple Time-Out or CRC Errors Occur

Visit the Hard Disk Drive Problems section of this site for more MS Knowledge Base articles on hard drives (the first item on the first page).

Benchmark tests

If you want to run benchmark tests on the processor, RAM, video/graphics card, and hard disk drive, download PCMark04 from http://www.futuremark.com/.

See the Diagnostics page on this site for information on how to use the KB, and for lists of KB articles applicable to the versions of Windows from Windows 95 to Windows Vista.

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Hard drive hex editors, also known as disk editors

A hex editor allows its user to view and edit almost any data on a hard drive - all kinds of files and their contents, and even the drive's file system (FAT32, NTFS, etc.) and master boot record (MBR). Plain text coded within executable (.exe) and similar files, can be edited easily by using a hex editor. For example, you can edit or remove such things as the Microsoft Internet Explorer heading that always appears at the top of every window that Internet Explorer opens.

A hex editor can display the contents of almost any file, and can provide enough information to enable you to determine what an unknown file is, or where it came from. File-oriented hex editors are usually optimised for the recovery of deleted files. You can locate, identify, rename, and save as a new file any file that was removed from the file system, which is what happens when a file is deleted. In other words, when a file is deleted, its reference in the file system is removed, but the data itself remains intact until it is overwritten by other data, so it is easily recoverable if it can be located by a hex editor.

Some hex editors are designed for other special purposes, such as allowing a knowledgeable editor to correct problems with the boot process itself, and with partitions and logical drives, including removing partitioning and formatting, or finding and undeleting lost partitions.

General-purpose hex editors can access so much raw data that they can be difficult to use, especially if you've never used one. However, special-purpose editors usually have simpler user interfaces that make using them much easier than general-purpose editors if they are being used for their intended purposes.

However, note well that because of their power, all hex editors can be dangerous to use and must be used with care by those who aren't knowledgeable in their use. For that reason, many hex editors have some form of disk-imaging built into them. If not, the user will be warned to create an image of the drive before attempting to make use of the editor.

WinHex is probably the best general-purpose hex editor. The program makes it a simple matter to locate almost any data written on a hard drive, and then edit and save it. A free trial version for home users is available for around $50, but a full drive-forensics version that has extremely sophisticated editing features costs around $500.

For links to more information other hex editors, use the search query sector hex disk file edit in a search engine.

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The SMART (S.M.A.R.T.) hard drive diagnostic program

If your hard disk drive(s) and BIOS support it, you should enable the HDD SMART Capability (setting) in the BIOS.

SMART is an acronym for Self-Monitoring, Analysis, and Reporting Technology.

A hard disk drive with this capability can notify you via a message on the screen (or even via a network server if the computer is part of a network) of a problem with the drive, which in many cases will allow the data to be recovered well before a major disk failure. It is not a cure-all for all impending disk failures, but it is well worth enabling.

You do not have to know if your hard disk drives support the feature. Just enable the setting for it in the BIOS, and it will automatically detect and switch the feature on in the drives that are supported. If, say you have two hard disk drives (HDDs), each of which support SMART, you will see a line for each of them saying that the feature has been enabled at start-up, just after the memory count.

Note that enabling SMART may cause spontaneous reboots in networked computers. Apparently SMART may be sending packets of data through the network even though there is nothing monitoring those data packets. Try disabling the HDD SMART Capability setting in the BIOS if reboots or crashes occur while you are on a network.

If SMART reports that a hard disk drive is faulty, but the drive continues working after you press the Esc key, you should transfer the data from it to the new drive with a utility such as the free XXCopy (only supported Win95/98/ME/NT/2000/XP/2003 up to August 2008) and then replace the drive as soon as possible. The drive may still be functional, so test it with the free diagnostic program that most hard-drive manufacturers provide from their sites. For example, if you have a Maxtor drive, run its low-level diagnostic program with its Factory recertification option enabled. Doing that may clear the warning generated by SMART. Some of the SMART diagnostic programs available on the web can provide data on exactly why a particular drive is generating a warning. Here is the links to one of them:

Active Smart - http://www.ariolic.com/

The free Belarc Advisor utility that identifies a computer's hardware and software, provides a report on SMART under its Drives category - e.g., "SMART status: Healthy".

Visit http://www.belarc.com/smart.html to read its page on SMART.

You can look for others by using a suitable search phrase (such as free smart diagnostic) in a web search engine.

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The hard-disk-drive user manual

The manufacturers of hard disk drives provide user manuals that are in the PDF format, which requires the a PDF reader such as Foxit. Such a manual contains all of the specifications for a particular drive, plus other information such as how to configure and install it.

If you have a brand-name computer, look in the Device Manager under Disk drives. If the manufacturer's device drivers have been installed for a particular model, its name will appear there. For example, if a computer uses a Seagate ST380021A hard disk drive, and the Seagate device drivers have been installed, the drive should appear in the Device Manager under Disk drives as ST380021A. But if the standard Windows device drivers have been installed, the make and/or model won't appear; you'll only see a description of the type of driver installed.

Seagate hard drives all have reference numbers that start with the letters ST. Only that number shows in the Device Manager for Seagate drives. But other manufacturers display both the manufacturer and the model's reference number. If there is only a model number, entering it in a search engine will reveal its manufacturer.

If there is no make or model information in the Device Manager, that information will appear on the drive itself. If you don't want to open the case to find out what it is, you can use the free Belarc Advisor, which creates an analysis of the hardware and software on a personal computer. Look for it under FREE DOWNLOAD at belarc.com.

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The warranty periods of IDE/SATA desktop hard disk drives

Many of the major hard-drive manufacturers went through a brief period in which they reduced the warranties for their hard drives from five years to only a year. It was short-lived because it did not inspire confidence in those manufacturers. Seagate announced that from July 26 2004 instead of a one-year warranty all of its desktop hard disk drives have a five-year warranty.

The website of the manufacturer of hard disk drives will provide details of the warranty cover of its drives.

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Descriptions of the death and near-death of two hard disk drives

1.

The computer seemed to be working slower and slower when bringing up or saving documents. Then a MS Word file refused to load. MS Word just sat there. The file was work-in-progress and had involved hours of work. All of a sudden Word brought the file up. As an unwise precaution, the operator tried to save the file under another name. Word refused to save it, and went back into waiting mode.

There were very audible sounds coming from the drive as it tried desperately to save the file. Then it gave up. The operator decided to shut the computer down in the hope that after a while of cooling down a restart would miraculously restore it to full health. But when the computer was restarted, the drive emitted a loud grinding noise, which increased in intensity until the computer suddenly died and gave off a burning smell. The operator switched it off at the mains immediately.

It turned out on examination of the drive that the drive had jammed on startup and the read/write heads over its platters were ruined. The effort the circuitry had put in to make the drive function had made the power supply unit overload. The computer was repaired, but the HDD was dead and the data on it lost unless a fortune was spent on employing a data-recovery outfit to recover it.

Hard disk drives can fail at any time, especially if they are nearing the end of their natural lives, which could be anywhere between three and ten years or more, depending on the type and quality of the drive and how much work it has to do. For instance, SCSI hard drives,which typically have five-year warranties, are built for extra-heavy duty. Therefore, adopting and implementing a data back-up strategy is essential if you don't want to lose data.

2.

The user suddenly discovered that he couldn't open ZoneAlarm (firewall) or use Norton Antivirus. When he entered his password on start-up, some of the characters changed. For instance, a full stop became a vertical line. Internet sites were blocked. Suspecting a virus was the cause, he found that he couldn't use online virus scanners. Then he used the diagnostic utility from Western Digital on the drive. It reported bad sectors and fixed them. The computer then began to work properly, but he backed up the system and replaced the hard drive, because it was clearly going to die properly soon.

When applications and programs fail to open, and characters change into other characters, it's a classic sign of some kind of hard-disk-drive failure.

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Recovering data from a hard drive that appears to be dead

If you have a hard disk drive that appears to be dead after you have tried everything you can think of to get it going, such as running diagnostic utilities on it, etc., there are three methods that can be used to revive it for long enough to recover its data. The methods can be summed up as follows: freeze it, hit it, and drop it.

Freezing the drive causes contraction of the mechanical parts that can free any stuck parts, or it can make failing electrical components remain within their operational specifications long enough for you to recover the data from the drive. You would place the drive in a waterproof bag and then place it in a freezer for several hours. After that period, you would install the drive in its PC (as the boot drive) as quickly as you can. If it works, you would then try copying its data to another hard drive or to recordable CD/DVDs as quickly as you can.

First hitting the drive, and then dropping it if doing that doesn't work, can also free any stuck parts, such as a stuck drive head.

If none of those options works and you have to recover the data on the dead drive, a data-recovery business will be able to recover it. The cost is usually high. To find data-recovery specialists, enter data recovery as the search query in a search engine.

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Backups: the various methods and media involved in creating an effective backup strategy

The question to back up or not to back up your system's data should not exist anywhere in your mind if you're running a computer that contains data that you value and therefore don't want to lose. You have to create backups and you have to be sure that they can be restored should the computer fail in such a way that its data becomes irrecoverable by using the ordinary, inexpensive means that are available to home computer users.

Click here! to go directly to the detailed offline and online backup information on the Software section of this website.

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Portable USB back-up drives

Flash drives, pen drives, thumb drives, jump drives, keychain drives, they carry many different labels, and they can employ varied technologies, but they all have a few features in common: they're compact, removable drives that attach to a computer via a USB port to add up to 64GB of portable back-up storage to a computer. The maximum capacity is constantly increasing. Visit this page to find out what the current maximum capacity of these drives is (256GB in Sept. 2011 with drives of 2TB planned).

Click here! to go directly to more information about these drives on this website.

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DVD video recorders that have inbuilt high-capacity hard disk drives

DVD video recorders are available now that have an inbuilt hard disk drive for the storage of video files at various levels of compression. The higher the level of compression, the greater the amount of video that can be stored. A 250GB hard disk drive can store over 400 hours of programming at the highest compression rate, and 100 hours in DVD quality. The drive allows the use of time-shifting technology that allows you to watch segments of a TV programme over and over while it continues to be recorded.

For more information on these machines and vendors of them, enter a search query, such as dvd recorder hard drive, into a web search engine.

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Iomega REV back-up drives

Iomega REV drives offer a cheap easy to restore back-up solution, hold up to 90GB of compressed data on a single disk, and come as internal or external removable versions, not much larger in size than a credit card, for the PC and Apple Mac that look much like USB floppy disk drives.

"For a fraction of the cost of traditional backup systems, the Iomega® REV drive gives you removable storage with hard disk performance that's up to 8× faster than tape. With compact, rugged 35GB disks that can store up to 90GB of compressed data you can back up all your files, protect your system and SAVE EVERYTHING (trademark software)...

Files can be accidentally overwritten, deleted or become corrupt. Laptops can be stolen. System hard drives can fail. But with Iomega Automatic Backup Pro and Norton Ghost for REV Drive software, you don't have to worry about it! Iomega Automatic Backup Pro (PC only) provides a 'set-it and forget-it' file backup solution, as well as file encryption and compression. Norton Ghost (PC only) for REV Drive provides full system image backups and restores directly from your REV disk for the fast and easy backup of an entire system. And, Dantz Retrospect (for Mac) supports complete system or incremental backups and can quickly restore an entire system, files from a specific point in time, or specific files from multiple backups."

For more information, read the FAQ page for REV drives on the Iomega site - http://www.iomega.com/rev/rev-faq.html.

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Wireless hard disk drives

Wireless network Access Points that can house a hard disk drive that is used for data storage are available. The ASUS 802.11g 54 Mbps WLAN Hard Drive Box (WL-HDD 2.5) is an example of one.

A user can save data to it via a wireless 802.11g adapter. But a suitable 2.5" notebook hard disk drive has to be purchased separately and then slotted into the case. The hard disk drive has to be configured through its web-based management utility, including partitioning the drive, not by the operating system (Windows\Linux). The partitions cannot exceed 40GB.

The box also supports both wired Ethernet and wireless network connections, but it can't be used to share an Internet connection. It has a USB port, but it can't be used to transform the unit into an external USB hard disk drive; it can only be used with USB flash drives.

For more information on this drive, copy and enter "Asus wl-hdd 2.5" (as is) into a search engine.

Wireless external data storage devices are now available. -

http://www.nextag.com/wireless-hard-drive/shop-html

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RAID: How to use software and hardware RAID as a back-up solution

If you run a mission-critical computer or network, you may have been told or read that the only way to protect your system from a hard disk drive failure is to use a setup called RAID, which stands for Redundant Array of Independent Disks in which two or more hard disk drives are configured to work together in a number of RAID configurations.

RAID - http://en.wikipedia.org/wiki/RAID

Note that the RAID controllers on most desktop PC motherboards are not true hardware controllers that don't require drivers or software to run drivers and software to run. This is because true hardware RAID controllers that don't require drivers or software to run cost hundreds or even thousands of pounds/US dollars.

In theory, hardware RAID should provide a performance advantage over software RAID, but in practice this is not the case. Moreover, rebuilding a failed array of disks takes roughly the same amount of time with both types of RAID.

Note also that if the PC's motherboard fails, you may not be able to access the data on a RAID array of disks until you replace it with the same model that has the same version of firmware installed.

Windows 7 provides software RAID (no earlier versions of Windows do), so if you use it, you are working independently of the hardware, so you can get at the data on the disks by connecting the disks to another Windows 7 PC, should the original PC fail irrecoverably for some reason.

Windows 7 Home Premium does not support software RAID, only the Professional, Ultimate and Enterprise versions of Windows 7 do.

A few notes on Software RAID under Windows 7 -

http://blogs.withalan.com/a-few-notes-on-windows-7-software-raid

And this Q&A on RAID and Windows 7 covers what most people need to to know about implementing a RAID 1 array of two mirrored hard drives for backup purposes: I want to set up a RAID 1 mirrored array of two hard disk drives for backup purposes on my Windows 7 Professional PC. Should I use hardware (BIOS) RAID or software RAID?

Providing redundancy originally meant that if one of the array is rendered redundant, another takes over so that no data is lost, but there are now many different RAID configurations that provide several methods of operating hard drives in an array of drives in order to protect the data and/or increase performance.

Using a RAID array of hard drives requires having a motherboard that has a RAID controller, or the use of a PCI RAID adapter card that is installed in a PCI slot on the motherboard.

If the RAID controller is incorporated in the PC's motherboard, the settings that enable RAID will be found in the system BIOS setup program. If necessary, refer to your the motherboard manual or brand-name computer's manual for information on the BIOS settings. You can make use of a utility, such as CPU-Z from cpuid.com, to identify the make and model of motherboard and then download a manual from its manufacturer's site.

Most current ATX motherboards provide six SATA 1.5 Gbit/s or SATA 3.0 Gbit/s ports, but a micro-ATX motherboard will probably only have two such ports. This limits the kind of RAID implementation that can be used to RAID 0 and RAID 1 implementations using only two hard drives.

Note that the SATA ports can be controlled by two SATA controller chips on the motherboard. RAID arrays of hard drives are implemented by a single controller. Therefore, if there are two controllers, you can only create a RAID array for each controller. Having six SATA ports doesn't necessarily mean that you can build a RAID array of six hard drives.

Advanced hard-drive controllers that are added to the system in the form of a PCI card have their own BIOS that loads independently of the system BIOS. The RAID controller should display its information at system startup briefly after the system BIOS has displayed its information. The key combination that opens the RAID controller's BIOS is provided. The setup page should display information on the status of the drives connected to the controller. Setting up a RAID array usually only involves enabling a few settings.

Note that Windows won't have the RAID controller's software device drivers, so it will ask you to press the F6 key so that you can install them from a floppy disk or CD/DVD disc that you prepared for that purpose. Windows won't ask for the drivers every time you start the computer, because it will install the drivers so that it can load them automatically at startup. You should create the driver floppy disk before you enable RAID in the BIOS.

This Q&A on this site provides information on how to create a driver floppy disk or CD-R disc: Windows XP won't install because it can't set up the motherboard's RAID Controller.

RAID configurations and modes of operation are usually employed using SCSI hard drives when used for enterprise servers, but it can be used with IDE PATA and SATA hard drives. Until the arrival of SATA 3.0 Gbit/s , using SCSI drives was the superior choice, but SATA 3.0 Gbit/s has emerged as a serious rival.

On a single system, RAID involves linking two or more hard disk drives on a motherboard that supports the software that allows them to function together in various ways designed to increase performance or protect the data on them should one of the drives fail. Providing redundancy means that if one of the array of hard disk drives is rendered redundant, the other drive or the other drives take over.

Remember that unless you purchase a separate PCI IDE controller card that supports RAID, a system's motherboard must support it if you want to use it. You can buy motherboards that support RAID from manufacturers such as Asus, MSI, and Abit.

Each drive in a RAID array should have the same capacity and be as identical as possible to the other drive(s) in order not to waste disk space or slow the configuration down. One drive that is slower than the others will slow the whole array down even if the other drives are very fast. The hard drives must be of the same type - PATA, SCSI, or SATA. One IDE motherboard connection and cable is required to connect every two PATA drives, but you need one SATA connection port and one cable for every SATA drive used in a RAID array.

As long as you install more than one hard drive in an external storage device, you can implement external RAID.

Comparing External RAID Housings : Backing Up Data To A Hard Drive -

"External RAID via eSATA and USB - Thanks to the intelligent SATA controller, which, alongside the port multiplier also provides a virtualization layer, multiple drives can now be addressed simultaneously in a single housing via either eSATA or USB 2.0. The operation of an external RAID cluster in the DAS [Direct attached Storage] devices is thus possible. To operate a RAID configuration, it is necessary for the housing to be used with at least two drives." -

http://www.tomshardware.co.uk/SansDigital-Superbox-FantomDrive,review-31247.html

RAID 0 to RAID 5 are the most commonly used methods of stringing an array of hard disk drives together on a system or a network.

RAID 0, also known as striping, spreads the system installation over two or more hard disk drives in order to increase performance. However, should one drive fail all of the data will be lost, so in order to retrieve it a system backup will have to be restored. If you create a RAID 0 array with two 160GB hard drives, Windows treats them as a single 320GB drive that is much faster than one of the drives.

RAID 1 mirrors the boot hard disk drive to a second drive. If one of the drives fails, the data remains safe on the other. A mirrored array is marginally quicker at reading data than a single drive, but it is no faster at writing data. The information is duplicated, so an array of two 160GB drives only has 160GB of disk space at its disposal. The RAID controller may be able to create the array without destroying the data on the boot drive, but note that building any other type of RAID array wipes all of the data from the hard drives that are used in its creation.

RAID 5. - Some recent (October 2006) motherboards support RAID 5, which requires three or more drives, increases performance, and provides security benefits. Data is spread across all of the drives and error-correction information is generated by the RAID controller. If one drive fails, the controller can reconstruct its contents from data on the other drives, and the array of remaining drives keeps working. When the faulty drive is replaced, the data is automatically rebuilt on it. The array's capacity is the capacity of all but one of the drives, so three 160GB drives produces a 320GB RAID 5 array.

RAID 5 needs powerful logic processing capabilities to control the simultaneous operation of several hard disk drives and to write data information across all disks in the stripe set while providing parity error control. The latter function does not require a particularly complex architecture, but as transfer rates increase, the process increases the processor's workload significantly. Hence the development of hardware RAID that makes use of a separate dedicated processor to handle the workload.

RAID 0+ 1 and RAID 10. - Some RAID controllers can combine striping and mirroring to form RAID 0+ 1 or RAID 10 arrays. At least four drives are required.

The array that most users use is to mirror the information on the working drive on at least one back-up drive so that if the working drive fails the system automatically switches over to using the back-up drive.

If you have read or been told that you have to have an SCSI interface in order to employ a RAID system, this is false. RAID is also now available for the IDE PATA interface, which is almost as good as SCSI, but is still considerably cheaper, and SATA 300 RAID looks as if it will knock SCSI RAID off its perch. SCSI drives are significantly more expensive than IDE PATA drives. Moreover, the SCSI interface usually requires an expensive PCI adapter card, whereas the IDE interface that is incorporated into most standard ATX motherboards can accommodate four IDE drives, and you can add more by using a Promise PCI adapter card. Motherboards are available with an incorporated SCSI controller, but they are usually much more expensive that standard motherboards.

Just remember that RAID only protects the system from hard-disk-drive failure. If, for example, the power supply unit (PSU) fails, the RAID system will fail with it. The same applies to the RAM, processor, network card, etc.

Therefore, the only way to protect a system - say, a network server system - is to have a back-up server that contains a duplicate of the data on the working server. And the system itself must be protected by an UPS unit - an uninterrupted power supply unit that protects the system from an unexpected power-supply failure.

Visit http://www.acnc.com/raid for more information on the various kinds of RAID arrays.

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Hard drives of different capacities can be used, but the capacity on all of the drives will be limited to the capacity of the smallest drive. The ease of setting up a RAID array depends on the utilities supplied with the RAID controller. Many controllers don't make it easy. For instance, it may be necessary to reformat the drives in a RAID array before installing the RAID software. You should always make a complete backup of any system before you attempt to implement any form of RAID. Remember that anything that disables or takes out one of the drives, such as a destructive attack by a virus or a power surge, will probably also take other any of the other drives in the array.

When simple mirroring of the main boot drive is used, if you delete files accidentally on the main drive, they'll also be removed from the mirrored drive(s). If the Master File Table of the main drive is corrupted, the mirroring will also corrupt the other drive(s). Add to that the innate problems that a RAID system can be prone to, which can often cause the loss of data, in my opinion using RAID is more trouble than it's worth. In my opinion, a better solution would be to back up or clone the system to an external USB 2.0 hard drive or across a network. An external hard drive uses its own power supply unit and is therefore unlikely to be taken out along with the computer's hard drives during a power surge, because you'll only connect it to the system in order to make back-ups or a new master image (clone) of the system.

Articles on RAID

RAIDing Windows XP: How to Install Windows XP on a RAID Array of Hard Disk Drives by Larry F. Byard -

"INTRODUCTION. This [11-page] article will show you step-by-step how to set up simple RAID configurations of hard disk drives and how to install Windows XP on them." -

http://www.duxcw.com/digest/Howto/mb/abit/kx7-333/raid1.htm

SSD RAID: Do You Want A Cheap Array Or One Larger Drive? - "You're on a budget. You want to know if it'd be better to stripe a couple of smaller SSDs or simply buy one larger performance-oriented drive. Today we're comparing one, two, and four 30 GB Kingston SSDNow V drives to Zalman's new 128 GB N-series SSD." -

http://www.tomshardware.co.uk/ssd-raid-performance,review-32060.html

RAID Scaling Charts, Part 1 -

"Most enthusiast and mainstream users would consider setting up a RAID array mainly for performance reasons - few really care about data safety. For this reason, the majority of arrays installed consists of only two drives, which run a simple RAID 0 stripe set. Haven't you ever asked yourself how these RAID arrays scale as you increase the number of hard drives? Is it worth it? When does the array hit bottlenecks? Administrators and über users be ready: here come the ultimate Tom's Hardware RAID Scaling Charts..." -

http://www.tomshardware.co.uk/raid-scaling-charts-uk,review-2340.html

RAID Scaling Charts, Part 2 -

For our RAID tests, we once again use Samsung HM321KJ SATA/300 drives. This time, we benchmarked RAID 5 and RAID 6 setups with three to eight hard drives.

http://www.tomshardware.co.uk/RAID-SCALING-CHARTS,review-2380.html

Unified Serial RAID Controllers for PCI Express -

http://www.tomshardware.co.uk/serial-RAID-controller,review-2387.html

If you want to read other articles on the subject or tutorials on how to set up a RAID system, enter a search phrase such as computer raid array in a web search engine.