HD Tach will test the sequential read, random access and interface burst speeds of your attached storage device (hard drive, flash drive, removable drive, etc). All drive technologies such as SCSI, IDE/ATA, 1394, USB, SATA and RAID are supported. Test results from HD Tach can be used to confirm manufacturer specs, analyze your system for proper performance, and compare your performance with others. HD Tach is very easy to use, quick, and presents data in easy to read graphs, including the ability to compare two storage devices on screen at the same time for easy analysis.
Bursts are provided only for your review. SSD’s don’t cache the same way HDD’s do, so burst testing typically results in figures that are lower than the sequential throughput figures.
HDTach also tends to turn in lower than expected figures for its sequential transfer test. This would typically mean you should discard them, but they become relevant when you consider how HDTach performs this particular test. It feeds the tested drive a continuous string of small sequential read requests. This is a single threaded operation, which means the SSD doesn’t get to see what’s coming next. The SSD has to quickly service rapid-fire requests one at a time, and this is why we see most SSD’s unable to reach full rated speed.
Random access times are presented for your persual, but this metric is more accurately evaluated by our IOMeter Transaction Time tests (later in this review).