Buying a computer for Vista ... and beyond

Hard drive strategies

In the world of hard drives, bigger in capacity is better. The good news is that bigger is getting less expensive as the days go by. A 320GB hard drive can be found for under US$100, and 500GB drives, once the platinum-card standard, have dropped to just below the US$150 mark.

The hot setup for desktop systems, of course, is RAID, in which combining two (or more) drives can net you a single virtual volume with the total capacity of the individual drives combined. As a side benefit, drives used in a RAID array are slightly faster than their stand-alone cousins.

RAID is an old technology, originally developed for mainframes so they could use comparatively cheap PC hard drives instead of the megabuck monsters they typically addressed. As it turns out, years later, the total storage afforded by combing drives on PCs is now slightly less expensive than buying a single drive of a similar capacity.

You'll often be able to pick among several configurations, usually RAID 0, RAID 1, RAID 0+1 and RAID 5. RAID 0 provides what's known as striping: Your data is written to disks alternately. This gives you a speed increase, but there's no attempt at fault tolerance. If one drive crashes, all your data is gone.

RAID 1 provides mirroring: Your data is written to one drive as your data destination and then rewritten to a second drive (mirrored) for fault tolerance. Although you're paying for two drives while only having the storage capacity of one directly available, your data is safe if either drive crashes.

RAID 0+1 wasn't part of the original RAID specifications but it provides just what its name implies: It's a striped pair of drives that's mirrored onto another striped pair, giving you speed plus fault tolerance.

RAID 5 is one of the more popular versions of the technology, but it does have a drawback. It works across several drives by striping data at the byte level while creating error-correcting code to maintain fault tolerance. If one drive dies, you can replace it with a new, blank disk, and your data can be recreated. Effectively, it's minimal waste with maximum performance and data integrity. The downside? The logic used to do the work can slow your PC's operations down. RAID 5 arrays are typically found in servers or as remote SAN or NAS configurations with their own smarts.

For your laptop, of course, you'll have just one hard drive, but you will usually have a choice of drive speed and capacity. Reject 4,800-rpm drive systems whenever possible. It's a value option to keep portable prices low, but it's not worth the trade-off in performance. In fact, a 5,400-rpm drive is acceptable only if a 7,200-rpm alternative is unavailable. Capacities as high as 300GB are in the works, and 200GB drives should already be available. Go for as much you can.

Naturally, because hard drive prices are so low, you're already considering an external drive to handle those incremental data backups that will make your life so much easier in the long run. Again, go large. External hard drives typically cost US$80 to US$150 more than their internal counterparts and are available in both single-drive and RAID configurations. Stick to devices that use 7,200-rpm drives, and keep in mind that an external Serial ATA drive is faster than a USB-attached drive.