Database Patterns

In the Database pattern the drive is processing a stream of requests to read and write 8KB random-address data blocks. The ratio of read to write requests is changing from 0% to 100% with a step of 10% throughout the test while the request queue depth varies from 1 to 256.

You can click the following link to view the tabled results for IOMeter: Database pattern.

We will build diagrams for request queue depths of 1, 16 and 256.

When the queue depth is zero, Western Digital’s drives are in the lead and close to each other, the Caviar Blue being somewhat behind the 2.5-inchers. It is only at a large number of read operations that the two previous-generation 7200rpm 2.5-inchers (Hitachi 7K200 and Seagate 7200.2) catch up with and outperform the Western Digital team. The high write response time of Seagate’s compact drives shows up here: their performance is lower at high percentages of writes than that of the other HDDs, and the new 7200.3 is inferior to its predecessor. It is a kind of regress instead of progress in the evolution of Seagate’s firmware.

When the queue depth is 16 requests, the drives can reorder requests and put all of their firmware algorithms to use. First place goes to the WD Scorpio Black which is only challenged at pure writing. The Seagate 7200.3 boasts an excellent ability of request reordering when it is receiving read requests only and takes second place then, but it has very low performance at every other load, losing even to its mediocre 7200.2 predecessor. You can also see that the 2.5-inchers are faster than the 3.5-inchers at high percentages of reads (the 5400rpm Scorpio Blue is quite competitive against the Caviar Blue, for example).

When the queue is increased to 256 requests, the peculiarities in the HDDs’ behavior show up even more. Seagate’s products finally demonstrate that they do have deferred writing. It is not aggressive in the 2.5-inch models while the 3.5-inch Seagate 7200.11 speeds up nicely at high percentages of writes. Otherwise, there are no changes among the leaders: the WD Scorpio Black is confidently first, enjoying a large lead over the pursuers. The Caviar Blue and the Scorpio Black share the remaining places on the podium. The Seagate 7200.3 gets closer to the others, yet still cannot leave its last place.

To wind up this part of the test session we will build diagrams with five queue depths for the two heroes of this review.

Judging by the left part of the graphs, the Seagate Momentus 7200.3 has rather good NCQ algorithms. Its deferred writing is very weak, though.

Western Digital seems to use the same firmware as we saw in our reviews of its 5400rpm 2.5-inch drives. This firmware has excellent request reordering algorithms, effective deferred writing, good scalability under increasingly higher load, and has no problematic loads. The diagram is a treat to our eyes.