Access time We measured average access time with IOMeter, using random 4 KB accesses. So as to view the potential gains linked to NCQ, these accesses were carried out with 1, 2, 4 and 8 simultaneous commands.
Standard access time, obtained with a single command, is quite high on these drives, with the 4 platter WD20EARS holding an unwanted record of 20.5ms! The 3 platter version does much better at 15.3ms, sharing first place among the 5400 rpm drives with the EcoGreen F3, preceeded by the 5900 rpm Barracuda LP. The EcoGreen F4 does a little less well than the F3 and nor does the WD20EADS excel here.
When it comes to the 7200 rpm drives, the Caviar Black does very well at 11.8ms, followed by the 7K2000 at 13.8ms. The Barracuda XT is however very disappointing with an access time of 16.7ms, which is strangely even higher than the LP!
NCQ does a good job in reads. Just for comparison, the Caviar Black’s best score of 7.6ms corresponds to speeds of 524 KB/s with 4 KB accesses. The fastest SSD up to now, the C300 128 GB, managed 143.2 MB/s, which is 280 times better.
The same test was carried out for writes. The numbers here are much better for hard drives because of the inclusion of a cache in writes, which does however make NCQ useless. The Caviar Black does best, followed by the 7K2000. The Barracuda XT is outperformed by three drives with lower rpm: the EcoGreen F3, the WD20EADS and the 3-platter EARS.