Hard Drives Gain Racing Stripes
Photograph: Marc SimonStripes are cool. Zebras confuse predators with them, and the Beach Boys made millions wearing them. But they're also very handy when it comes to hard drives. RAID (Redundant Array of Independent Disks) comes in a variety of flavors. The one that is most commonly used with desktop systems, RAID Level 0, isn't really a type of RAID at all (thus, RAID "0") because it doesn't provide any redundancy.
RAID 0 stripes (or parcels out) data across multiple drives to create one larger logical drive, delivering much faster sustained reads and writes along with sometimes slightly slower random access. An analogy would be to have multiple waiters instead of one serving dinner to your table: It takes a while longer to organize things; but then the food and drink (or data, in this case) flow to you much faster.
Another advantage of RAID 0 is relatively low cost. Drive vendors charge a hefty premium for their largest models, so you can achieve a better cost per gigabyte by combining multiple smaller-capacity drives. Today, a single 400GB drive costs about $350, whereas two 200GB units combined into a single 400GB logical drive cost about $250, plus $20 to $50 for a RAID controller card if you need one.
Most mainstream add-in RAID cards and motherboards also support RAID Level 1 (mirroring), which writes the same data to two drives at once for data redundancy in case one of the drives fails. In addition, some cards let you combine RAID 0 and RAID 1 (RAID 0+1) so you can mirror a pair of striped drives (if you have four drives).
The Raptor WD740GD posted the fastest or the second-fastest time on every RAID 0 test. Its biggest gains came on our large-file and file-and-folder tests, with jumps of 32 percent and 43 percent over a stand-alone Raptor. This RAID setup also outperformed the average single SATA drive in some--but not all--of our tests (click here for more details).
You don't have to graduate to a 10,000-rpm drive to see performance improvements with RAID, though. When configured using RAID 0, Western Digital's SATA Caviar SE WD2500JD improved its times by 26 percent and 33 percent, respectively, on our large-file and file-and-folder tests.
Given the sizable boosts we saw in our tests, we'd recommend a RAID setup to anyone seeking optimum PC performance. Just be sure to back up regularly: The big disadvantage of RAID 0 is that if one drive goes bad, you lose the data on both.
Jon L. Jacobi
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