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Introduction - Part Two

We mentioned that the rules have changed, and this is true in a number of respects. For one thing Parallel ATA belongs in the past, and any hard drive that you buy these days is sure to use a SATA interface. SATA has a number of advantages over PATA as the connecting cables are much slimmer, which makes them easy to route round the inside of your case. In addition SATA cables enable cool air to circulate far more freely than the wide ribbon cables used on PATA drives which makes the installation of an extra SATA hard drive or two quite simple. Added to that you can hot plug SATA drives, as long as the controller supports it. This feature may not be crucial to your buying decision but there is a certain satisfaction in plugging in a new hard drive without first shutting your PC down.

You also have to consider the original thinking behind RAID. Less than ten years ago a 1GB hard drive cost £100 and more recently we have been limited by the capacity of hard drives. Back in 2001 the IBM 75GXP required five platters to achieve its huge capacity of 75GB. These days, that’s all changed so for instance, a 250GB Hitachi T7K250 drive costs £78 at www.overclockers.co.uk, which works out to 31p/GB, while you’ll pay about 50p/GB for a 500GB Hitachi 7K500. This means that if you simply want a decent amount of storage you have no need for a RAID array on a desktop PC. You can fit your entire life on a single 250GB drive.

There is a specific exception to this statement. The Western Digital’s WD740 Raptor is popular because of its 10,000rpm spin speed but it only has a capacity of 74GB so you may want to use RAID to create a ‘big’ Raptor. You’ll note that we are ignoring the hardcore enterprise market, which tends to deal with monumental amounts of data, such as the nuclear research at CERN or cataloguing the Internet at Google. These types of institutions really do need as much storage capacity as they can get their hands on.

But returning to price per gigabyte, we see that cost isn’t much of a factor these days, so the ‘Inexpensive’ part of RAID has become, ahem, redundant. This means that there are only two reasons to run RAID on a desktop PC; either you want to speed up your PC or you want to ensure that your data is secure. In the ideal world you’d be able to both speed up your PC and make your data more secure. However a few simple benchmark tests show that this isn’t possible. Actually there’s another simple way to tell that you can’t have the best of both worlds because if it was possible you can be sure that Dell, HP, Evesham, Mesh and the rest would have latched on to it ages ago. Instead the vast majority of PCs are sold with a single hard drive.

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