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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 that 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 IOps rather than response times for these tests. Click the buttons below the graph to switch between SSDs.

From crest to trough, the 960 EVO 250GB's plot doesn't look all that different from the 850 EVO 250GB's. Clearly IOMeter write tests are not the drive's strong suit. The 1TB version, on the other hand, hits an insane peak that even the 960 Pro can't match. Even after it's used up all its caching tricks, the 960 EVO 1TB writes at incredible speed. 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.

An insane peak indeed. The 960 EVO 1TB sets a new record for peak random write rate in our sustained test, beating even the datacenter-class DC P3700. The P3700 still holds the crown for steady-state performance, but the EVO 1TB snags second place. The 960 EVO 250GB again manages to beat the 850 EVO 250GB, but the margin is smaller than we might have expected.

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.

The 960 EVO 250GB simply isn't fast enough in IOMeter to convert its NVMe capabilities into any sort of meaningful scaling. But the 960 1TB does not disappoint, ramping up smoothly to QD32 before starting to taper off. Let's look at the Samsung lineup together to get a sense of where the 960 EVOs fall.

As in all the prior tests, the 250GB EVO improves upon its predecessor, but only by a small margin. The 1TB EVO's performance is only contested by the 960 Pro, whose scaling curve is noticeably steeper. All those dollars have to buy you something, after all.

The 960 EVO 1TB passed all of our IOMeter tests with flying colors. The 960 EVO 250GB offered lightning-fast reads, but its writes proved only a little better than the 850 EVO 250GB's. Perhaps real-world workloads will better showcase the drive's capabilities.