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Disk Response Time and IOMark: Average Positioning Speed

In this test IOMeter is sending a stream of requests to read and write 512-byte data blocks with a request queue of 1 for 10 minutes. The total number of requests processed by the HDD is over 60 thousand, so we get a sustained response time that doesn’t depend on the HDD’s buffer size.

The Western Digital RE4-GP is ahead at reading. Western Digital squeezes everything out of the heads of its server series. Those 14 milliseconds is an excellent response time for a 5400rpm drive. Second place goes to the Seagate LP which is 0.5 milliseconds worse than the leader. The 2TB WD Caviar Green is good, too. It enters the top three and even beats the Seagate 7200.11, despite the latter’s higher spindle rotation speed. The 1.5TB model and the video-optimized product deliver modest results here. We suspect that the AV-GP has somewhat slowed-down heads. It is the heads that produce the most noise whereas home electronic appliances are expected to be quiet.

We’ve got the same leader at writing: the HDD from Western Digital seems to make good use of its 64 megabytes of cache. Its response time is twice better than at reading. Among the other results we can note the high response time of the Seagate 7200.11. As we know from earlier tests, this drive’s electronics gets “stifled” when processing small-size data chunks.

In the next test the drive is being bombarded with read requests like in the response time test, and we calculate the difference between the LBA addresses of the previous and next requests and divide it by the time it took to perform the request. In other words, we have the distance (in gigabytes) the drive can run through in 1 second. The results are averaged and compared.

The 2TB models are superior here. We have found out in the previous test that the Western Digital AV-GP has slowed-down heads but even this model is better than the 1.5TB ones. Take note that it is not high-density platters (the Samsung has them, too) and not the 4-platter design (the Seagate 7200.11 uses it as well) but the combination of the two that is the decisive factor here. A low response time – as the consequence of quick heads – would be appropriate, too. It helps the Western Digital RE4-GP win this test.

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