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Sustained and scaling I/O rates
Our sustained IOMeter test hammers drives with 4KB random writes for 30 minutes straight. It uses a queue depth of 32, a setting which should result in higher speeds that saturate each drive's overprovisioned area more quickly. This lengthy—and heavy—workload isn't indicative of typical PC use, but it provides a sense of how the drives react when they're pushed to the brink.

We're reporting input-output operations per second (IOPS) rather than response times for these tests. Click the buttons below the graph to switch between SSDs.


To show the data in a slightly different light, we've graphed the peak random-write rate and the average, steady-state speed over the last minute of the test.

This test shows that the SP550 doesn't wholly rely on SM2256's pseudo-SLC caching as a crutch. It beats the planar TLC competition—the Trion 100, Trion 150, and BX100—by a solid margin. The SP550's steady-state write rate is even fast enough to keep up with some MLC-equipped terabyte-class drives, like the SSD370 and the Reactor. Chalk this up as a win for the SP550, as it's proved to be the best-performing planar TLC drive we've tested when it comes to sustained random write performance.

Our final IOMeter test examines performance scaling across a broad range of queue depths. We ramp all the way up to a queue depth of 128. Don't expect AHCI-based drives to scale past 32, though—that's the maximum depth of their native command queues.

For this test, we use a database access pattern comprising 66% reads and 33% writes, all of which are random. The test runs after 30 minutes of continuous random writes that put the drives in a simulated used state. Click the buttons below the graph to switch between the different drives. And note that the P3700 plot uses a much larger scale.


As always, we don't expect consumer-oriented drives to scale particularly well, but the SP550 actually does seem to scale meaningfully at least until QD8. Let's take a look at it in context.


As it did in our sustained tests, the SP550 comes out looking quite a bit better than the Trion 150 and BX200. It's a little of shy of catching the 850 EVO, but hey, this is planar NAND, after all.

This drive's sequential and random rates may have been a bit of a mixed bag, but this page of tests has been all good for the SP550. Let's see what it does with some real-world workloads.