Iometer IOPS Performance

Iometer is an I/O subsystem measurement and characterization tool for single and clustered systems. Iometer does for a computer’s I/O subsystem what a dynamometer does for an engine: it measures performance under a controlled load. Iometer was originally developed by the Intel Corporation and formerly known as “Galileo”. Intel has discontinued work on Iometer, and has gifted it to the Open Source Development Lab (OSDL). There is currently a new version of Iometer in beta form, which adds several new test dimensions for SSDs.

Iometer is both a workload generator (that is, it performs I/O operations in order to stress the system) and a measurement tool (that is, it examines and records the performance of its I/O operations and their impact on the system). It can be configured to emulate the disk or network I/O load of any program or benchmark, or can be used to generate entirely synthetic I/O loads. It can generate and measure loads on single or multiple (networked) systems.

To measure random I/O response time as well as total I/O’s per second, Iometer is set to use 4KB file size chunks over a 100% random sequential distribution at a queue depth of 32 outstanding I/O’s per target. The tests are given a 50% read and 50% write distribution. While this pattern may not match traditional ‘server’ or ‘workstation’ profiles, it illustrates a single point of reference relative to our product field.

All of our SSD tests used Iometer 1.1.0 (build 08-Nov-2010) by Intel Corporation to measure IOPS performance, using a SandForce-created QD30 configuration: 4KB 100 Random 50-50 Read and Write.icf. The chart below illustrates combined random read and write IOPS over a 120-second Iometer test phase, where highest I/O total is preferred:

In our Iometer tests, which are configured to use 32 outstanding I/O’s per target and random 50/50 read/write distribution, SandForce SSDs generally outperform the competition when tested with this large queue depth. Previously, the OCZ Vertex 4 SSD delivered the best combined IOPS performance we’ve seen from any SATA-based SSD with 83,494. That was before the OCZ Vector 150 produced 88299 for a new all-time top score, or the Vertex 450 with 87323. OCZ’s Vertex 3 Max IOPS Edition produced 83117, followed by the Intel SSD 520 Series at 80,433 peak combined IOPS, then the Intel SSD 335 Series with 80015.

It should be noted that nearly all modern SSDs deliver I/O far beyond the needs of multi-tasking power users and hardcore gamers, and would be ideal for workstation systems running utilizing virtual machines.

In our next section, we test linear read and write bandwidth performance and compare its speed against several other top storage products using EVEREST Disk Benchmark. Benchmark Reviews feels that linear tests are excellent for rating SSDs, however HDDs are put at a disadvantage with these tests whenever capacity is high.