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.

The new and previous gen Vector models perform right at the top in these tests. It was good to see the lower capacity model perform right up there with the larger ones. Normally the reduced number of available channels shows negatively in raw IOPS performance. Not the case here.

In case you were curious as to why the two 840 models appear to be dogfighting each other, the charts are now presented in the order in which they are run. As they are in a back-to-back sequence, with no breathing room given to the SSD between the tests, the 500GB 840 EVO fills its SLC cache in the middle of the database test, and the reduced write speeds impact performance through the final workstation sequence as well. A smaller capacity EVO would fill its cache sooner, while the 1TB EVO made it through the entire sequence at full speed.

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