HD Tach is a physical performance hard drive test that uses a special kernel mode VXD to get maximum accuracy by bypassing the file system.
The HD Tach sequential read test is a little bit different from other benchmarks.
Most benchmarks create a file on the hard drive and test within that file. The problem is that modern hard drives use a zone bit recording technique that allows different read speeds depending on where the data is located. Data on the outside of the drive is much faster than data recorded on the inside.
With this test we NEVER reach advertised speeds, so please don't worry about that. It is the nature of the test. But here again is something we noticed in the HDTune sustained tests as well, the Intel 320 has a hard time keeping up with its competition.
When we look at write performance we see slightly slower scaling, we still get close to 163 MB/sec in this test, and that's okay enough, nothing rather exhilarating though.
In addition to sequential read performance, HD Tach tests the drive's random access time. Random access is the true measure of seek speed. Many drives advertise sub 10 millisecond seek speeds, but seek speeds are misleading. Also again, without a physical head that needs moving around, the SSDs are just so fast as they have no mechanical moving parts. Here obviously... the smaller number is better, 0.1 ms.
The Burst speed measured in HD Tach was 248 MB/sec by the way. Check the test result here.
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