How We Test HDDs And SSDs

Advanced Workloads

It wasn't enough for Futuremark to release the best traces we've benchmarked. The company went on to produce the best client storage metric ever created. The Storage Consistency Test works a drive though several stages of performance. For years, we knew that SSDs should be evaluated in three dimensions. The 2D look yields a basic picture of performance, but lacks the depth of steady state and performance recovery.

Precondition

1. Write to the drive sequentially up to its reported capacity with random data, write size of 256*512=131072 bytes.
2. Write through a second time (to take care of over-provisioning).

Degradation

1. Run writes of random size between 8*512 and 2048*512 bytes on random offsets for 10 minutes.
2. Run performance test (one pass only). The result is stored in secondary results with name prefix degrade_result_X where X is a counter.
3. Repeat steps one and two eight times, and on each pass increase the duration of random writes by five minutes.

Steady State

1. Run writes of random size between 8*512 and 2048*512 bytes on random offsets for final duration achieved in degradation phase.
2. Run performance test (one pass only). The result is stored in secondary results with name prefix steady_result_X where X is a counter.
3. Repeat steps one and two five times.

Recovery

1. Idle for five minutes.
2. Run performance test (one pass only). The result is stored in secondary result with name recovery_result_X where X is a counter.
3. Repeat steps one and two five times.

Clean Up

1. Write to the drive sequentially up to its reported capacity with zero data, write size of 256*512=131072 bytes.

The performance consistency test involves 18 individual runs using the same workloads as the standard test. The result is one long text file with several useful bits of data. We use the overall throughput from each combined test run and the overall latency.