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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 this link to view the tabled results for IOMeter: Database pattern.

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

 

There is nothing unexpected at the minimum request queue depth. The three modern 2.5-inch drives are close to each other. The Constellation ES is ahead due to its lower response time and more effective deferred writing whereas the 7200.4 doesn’t do much deferred writing and has low results as the consequence.

The graphs become more complicated when the queue grows longer. The Constellation ES is still unrivalled at pure reading and writing but is not that good under mixed loads. The 7200.4 is very good at reading but poor at writing. The new XT delivers stable performance, being always ahead of the Toshiba as well as the Hitachi. The latter is poor at mixed loads, too.

At the maximum queue depth the Momentus XT takes second place, behind the unrivalled Constellation ES.

The next diagrams show the performance of each HDD at five different queue depths.

The Constellation ES behaves exactly like the 1-terabyte model from the same series that we tested before. It has aggressive read reordering algorithms and effective deferred writing. But it doesn’t (or cannot) do both at the same time. The Momentus XT and the Toshiba look more balanced. They have all the optimizations, too, but apply them in such a way as to deliver high speed (especially for their not-very-fast read/write heads) at any loads. Well, it is good that the firmware flaws we could see with the Momentus 7200.4 (it has too weak deferred writing) seem to have been left in the past.

 
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