Performance in Intel IOMeter

Disk Response Time

In this test IOMeter is sending a stream of requests to read and write 512-byte data blocks with a request queue of 1 for 10 minutes. The total number of requests processed by the disk array is over 60 thousand, so we get a sustained response time that doesn’t depend on the cache buffer size. The array cannot store all the requests in its cache and deliver a fantastically high performance.

Well, it looks like we’ve got a Samsung that works in quiet mode (with slowed-down heads), just like in the previous review. But in our review of RAID arrays based on 400GB drives we could only observe a negative effect from the quite mode under low loads in IOMeter:Database. So, it only makes the test session the more interesting. Take note that the quiet mode has no effect on the drive’s write response time – the caching of write requests neutralizes it effectively.

Let’s get back to the results, though. First of all, we can note the obvious thing once again: the array type does not influence the array’s read response time. This parameter is only determined by the characteristics of the HDDs the array is built out of.

Writing is a different story as it is affected by the caching algorithms. The situation is even more complicated since we’ve got two caches: in the controller and in the HDDs. The Western Digital RE3 is the best in this test. Its write response time is excellent irrespective of the array type.

The Seagate drives produce curious results here. The two new models with large cache are worse than the older models in RAID0. So, better specifications do not always mean better performance. The old Seagate ES is considerably superior to its desktop counterpart. The new series feels much better than the older one in RAID10, and the response time of the desktop and enterprise models is almost the same in each pair. In RAID5 the new series is better than the older one but the new enterprise model is inferior to the new desktop model whereas within the older series it is just the opposite.

The Hitachi and the Samsung are very poor at writing in RAID5. The Western Digital RE2 produces mediocre results all the time.