Iometer is a powerful open source synthetic benchmarking tool, able to simulate the effects of a wide variety of software loads and circumstances on either individual hard disk drives and complete drive arrays. In the past we've chosen not to include it due to bit-tech's traditional preference towards real world benchmarks. However, to correctly check for drive stutter caused by extremely high random write latencies there aren't a great deal of options, so we've finally decided to include Iometer in our hard disk testing suite.
For our Iometer testing we subject the drive to random read or write commands of 4KB, with three outstanding I/Os to simulate high level multi-tasking over a 4GB portion of the drive. We ran each test for two minutes, repeating three times to ensure we recorded an accurate result.