IOMeter v2006.07.27 – IOps

Iometer is an I/O subsystem measurement and characterization tool for single and clustered systems. It was originally developed by the Intel Corporation and announced at the Intel Developers Forum (IDF) on February 17, 1998 – since then it got wide spread within the industry.

Meanwhile Intel has discontinued to work on Iometer and it was given to the Open Source Development Lab (OSDL). In November 2001, a project was registered at and an initial drop was provided. Since the relaunch in February 2003, the project is driven by an international group of individuals who are continuesly improving, porting and extend the product.

Light desktop usage sees QD figures between 1 and 4. Heavy / power user loads run at 8 and higher. Most SSD’s are not capable of effectively handling anything higher than QD=32, which explains the plateaus.

Regarding why we use this test as opposed to single-tasker tests like 4KB random reads or 4KB random writes, well, computers are just not single taskers. Writes take place at the same time as reads. We call this mixed-mode testing, and while a given SSD comes with side-of-box specs that boast what it can do while being a uni-tasker, the tests above tend to paint a very different picture.

Now with that out of the way, lets look at the Vertex 4. You’ll notice the 1.30 firmware was showing some very high figures at QD 1-2, but it tapered off way earlier than it should have, meaning it started to self-limit at heavier parallel workloads. With the 1.52 firmware we saw big improvements on the higher end of three out of four tests, but low Queue Depth performance suffered. The former indicates a controller capable of some very low latencies, while the latter indicates there is plenty of headroom that can be exploited in the way of firmware optimizations. The trick now is to see both of these combined to yield the best of both worlds, which based on what I’ve seen here, should be possible through the release of a future firmware update.

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