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Last time, we began looking at hard-drives, how they work, how they?re measured and a couple of best-practice things to do to maintain them. Today, I want to look further at hard-drives, describing the different types of drive, and which one is best for you depending on your requirements.

Most hard-drives in standard PCs, are IDE type drives. That stands for Integrated Device Electronics, and the name derives from a time when it was a new idea to move some of the basic intelligence of the device from the motherboard onto the actual drive.

Most of your magnetic storage devices are IDE connected devices, and are recognised as connecting to the internal parts of your system using a two-inch wide, grey ribbon cable. On most systems, there are at least two IDE connections on the motherboard, and most ribbon cables have two connections, meaning that at least four devices can be connected (we will cover CD-ROMs etc in a later article).

Your hard-drive will usually be recognised as Drive C:\ in your computer, and everything that resides on your computer resides beneath it (all programs, all letters you?ve written, your e-mail - everything). You can see how much space your hard-drive has by ?right-clicking? on the ?Drive C:? icon in ?My Computer?, and selecting properties. A pie-chart will show up, indicating how much of your drive has been used and how much is available.

Something else worth covering here, is scan-disk. If you prematurely shut down your system, before it has had time to tidy itself up, the next time you switch on, you will probably be faced with a scan-disc in operation, which will carefully check that what the PC thinks is on the disc IS actually there. This is a precautionary measure, and you should not be alarmed ? scan disc rarely encounters any major problems and should complete its check without any alarm.

There are two other hard-drive connection technologies worthy of mention: 1, is SCSI (Small Computer System Interface). SCSI drives are usually very expensive, but are recognised as being of superior reliability and performance, and ? most useful to business customers ? allow multiple-access (something that IDE drives aren?t very good at). Thus, SCSI drives tend to be found in large servers, or storage arrays (we?ll cover these too, much, much later).

The second is SATA (standing for Serial ATA (Advanced Technology Attachment), a relatively new technology, that will probably take over from IDE in time, and overcomes some of the access speed constraints inherent in IDE and other device technologies. In addition, its small cable form-factor (it does not use the wide ribbon as IDE does), allows for greater air-cooling flow within, ever shrinking, smaller designed PCs.

Another acronym you will sometimes hear being bandied around is RAID. RAID stands for Redundant Array of Independent or Inexpensive) Disks, and, in a nutshell allows several drives to be connected together in such a way that Windows sees all drives as one big drive. Thus six drives, each of 10GB assembled using RAID, will appear as one large 60GB drive. This method is useful for performance, as data can be written to each disc simultaneously, leading to blistering performance.

RAID is also used, though in a different configuration, to ?mirror? data between two drives. Let?s explain: With your bog-standard IDE hard-drive, if the device fails, that?s it: Dead, and ? more critically ? all your data gone: Irretrievable. With RAID configured to mirror data, the same information is written to two drives simultaneously. As far as Windows is concerned, it is writing to one device, and it is the RAID technology that is writing it to two different drives.

The benefit to the user is that it is highly unusual for two drives to fail at the same time, thus, if one fails, your data is safely stored on the other, and, whilst your PC supplier obtains a replacement for the failed device, you can continue to operate. When the replacement drive arrives, it is a relatively simple operation to get it back as one ?side? or plex to use its correct term, of the mirror.