The benchmarks presented above strongly indicate that there are very slight performance differences between the four tested drives. We theorized that miniscule differences in average seek time were responsible for this; the IOMeter access time backs up this theory. The IOMeter test also sheds some light on just how much seek time difference is required to produce these small differences, as well as serving as a "consistency check" - verifying that the results correlated with other tests in both IOMeter and WinBench.
It's important to point out that the performance differences observed in these trials are minute at best. Such differences certainly aren't noticeable to any human being, nor are they detectable by the vast majority of benchmarks (the Business WinMark scores don't reflect our findings, and it could be argued that the A-B-D-C pattern of the High-End scores is coincidental since only 1 of the 7 High-End subtests follows this pattern). Therefore, a difference of 1 or 2 IOs/sec in IOMeter is hardly significant in our opinion; in fact, we initially assumed that these differences were caused by IOMeter itself. Further investigation, however, reveals that there is indeed a pattern to these differences. IOMeter access time tests reveal the same pattern, strengthening the original results.
These findings should come as no surprise. After all, hard drives are mechanical devices with physically moving parts. Very small differences in performance should be expected; it would be unreasonable to expect each and every drive to have the exact same seek speed.
I'm pleased that I had the chance to examine four drives for performance differences. It was an issue that I had thought about in the past, but never had a chance to test on my own. That being said, I hope you have enjoyed my first article. Comments are welcome -- via email, or the discussion forums.