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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 these links to view the tabled results for the IOMeter: Database pattern:

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

The Maxtor Atlas looks much better than the others at the minimum queue depth. It can do more operations per second than its opponents thanks to lower response time. Its advantage at mixed loads is especially impressive. We guess the only weak spot of this HDD is its small cache buffer. It is inferior to the HDDs with 16MB cache in terms of deferred writing efficiency. Seagate’s two latest generations look better than the others, too. And we can recall that their response time is good, too.

The secret of the low writing performance of the 73GB Seagate 15K.5 and the Hitachi 15K147 is revealed: they do not have deferred writing at all.

When the queue depth is increased to 16 requests, each HDD begins to display its unique character, showing the peculiarities of its firmware. The Maxtor is very good among the smaller-capacity models but its sluggishness at writing is now obvious. Both drives from Fujitsu outperform it easily at high percentages of writes. The 73GB Seagate 15K.5 and the Hitachi 15K147 are still poor: their graphs are nearly horizontal lines that lower steadily towards higher percentages of writes.

The Seagate 15K.6 is the best of 146GB drives although its unexpected slump at 80% writes spoils the picture somewhat. This diagram is actually very informative as to the progress of the HDDs: the products from Fujitsu and Seagate improve with each new generation even under server loads which are highly sensitive to firmware and almost indifferent to recording density.

When it comes to larger and newer HDDs, Seagate’s two latest generations prove to be faster than the others. The rest of the HDDs go close to each other, the 10,000rpm Seagate NS.2 keeping up with them, too. The 300GB Fujitsu MBA3 RC is a disappointment. Its firmware seems to ponder for a long time over each request, being only more or less good at writing.

At a very long queue depth (it is indeed very long, and if you see such a queue in an operating server, you should think about upgrading its disk subsystem) the Hitachi 15K147 and Fujitsu 146GB MBA3 RC go ahead whereas the old Seagate 15K.4, 15K.5 and the Maxtor turn to be slow. The Seagate NS.2 is uncompetitive to the HDDs with higher spindle speed under such a high load.

 
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