Among its many features, diglloydTools DiskTester offers a run-area-test command that can be used for relatively fast characterization of drive performance across its capacity. The results can be graphed to get a good idea of the drive performance.
For example, suppose a high performance RAID is envisioned: one laggard can cut the performance, since the slowest drive determines the peak speed.
As shown below, 8 samples were tested, and one of those eight is a significant laggard; this slower drive is best set aside as a cold spare or backup drive.
While DiskTester can test any number of drives simultaneously (via command line), testing should take care not to saturate the bandwidth; for example four fast hard drives can demand almost all of the Thunderbolt v1 bandwidth, and other devices on the bus could suck up bandwidth, disturbing the results.
Click for larger graph.