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.

When it comes to random mixed IOPS performance, die counts most definitely matter, especially as IO requests are piled up on the controller. Limited dies (4 and 8) of the two smallest capacities effectively hobble their performance when hit with heavy workloads. The 80GB 310 Series is able to beat out the 60GB due to a greater number of (lower capacity) dies coupled with an Intel G2-style controller using one more data channel than SandForce in this configuration.

On the flip side, controller / firmware improvements over the past year have enabled the largest two capacities to beat out the older SSD 520 in nearly all of these heavy duty tests – an impressive feat considering their size.

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