The Toshiba OCZ RD400 (256GB, 512GB, 1TB) M.2 PCIe SSD Reviewby Billy Tallis on May 25, 2016 8:02 AM EST
Mixed Random Read/Write Performance
The mixed random I/O benchmark starts with a pure read test and gradually increases the proportion of writes, finishing with pure writes. The queue depth is 3 for the entire test and each subtest lasts for 3 minutes, for a total test duration of 18 minutes. As with the pure random write test, this test is restricted to a 16GB span of the drive, which is empty save for the 16GB test file.
The RD400 sets new records for mixed random I/O performance with a substantial lead over the Intel 750 and Samsung 950 Pro.
The RD400's power consumption is also record setting, but its efficiency is closer to normal for a PCIe SSD on account of the high power consumption yielding high performance.
Most of the RD400's overall performance advantage is due to strong performance in the final phase of this test where the workload is 100% random writes. The 400GB Intel 750 has even higher random write speed, but performs lower on the other phases of this test.
Mixed Sequential Read/Write Performance
The mixed sequential access test covers the entire span of the drive and uses a queue depth of one. It starts with a pure read test and gradually increases the proportion of writes, finishing with pure writes. Each subtest lasts for 3 minutes, for a total test duration of 18 minutes. The drive is filled before the test starts.
The RD400 handles a mixed sequential workload better than anything else and more than twice as fast as SATA drives.
As usual, the RD400 needs plenty of power to deliver its high performance. The Samsung 950 Pro is a bit more efficient despite being slower.
Performance across the mixed sequential test is usually a bathtub curve with the balanced mixes having the lowest performance. The RD400 bottoms out around the theoretical limit for SATA drives, which is substantially better worst-case performance than anything else. The 950 Pro has much better performance during the pure read start of the test but falls behind in the middle of the test and doesn't bounce back as much at the end.