Random Read & Write Patterns
Now we’ll see the dependence between the drives’ performance in random read and write modes on the size of the data block size.
We will discuss the results of the disk subsystems at processing random-address data in two versions. For small-size data chunks we will draw graphs showing the dependence of the amount of operations per second on the data chunk size. For large chunks we will compare performance depending on data-transfer rate in megabytes per second. This approach helps us evaluate the disk subsystem’s performance in two typical scenarios: working with small data chunks is typical for databases. The amount of operations per second is more important than sheer speed then. Working with large data blocks is nearly the same as working with small files, and the traditional measurement of speed in megabytes per second becomes more relevant.
The drives deliver similar speeds with small data chunks but a few models stand out. Seagate’s new models have high results while the Western Digital WD7500AYPS is rather slow. The updated WD7501AYPS is as fast as the other HDDs as if its spindle rotation speed were 7200rpm.
The new Barracudas are unrivalled with large data chunks although the Samsung is good, too. The updated GP series model from Western Digital is surprisingly good again as it is not only faster than its mate but also outperforms Seagate’s 7200.10 and ES series drives and is almost as fast as the Western Digital RE2. But all these drives have a spindle rotation speed of 7200rpm rather than 5400rpm!
Seagate’s 7200.11 is good again. The enterprise ES.2 model is not so good at writing small data chunks, although outperforms most of the four-platter models. Surprisingly enough, the Hitachi competes with the leader and the Samsung follows the leaders closely. And the biggest surprise is that the WD7501AYPS is nearly as fast as the Samsung!
Seagate’s new HDDs are in the lead when writing large data chunks, the enterprise version being somewhat slower than the desktop one as usual. The Western Digital Caviar Blue takes third place in tough competition with its RE2 series mate and with the Samsung drive.