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Samsung 840 EVO SSD: Tested At 120, 250, 500, And 1000 GB

Results: 4 KB Random Reads

Technically, "random" translates to a consecutive access that occurs more than one sector away. On a mechanical hard disk, this can lead to significant latencies that hammer performance. Spinning media simply handles sequential accesses much better than random ones, since the heads don't have to be physically repositioned. With SSDs, the random/sequential access distinction is much less relevant. Data are put wherever the controller wants, so the idea that the operating system sees one piece of information next to another is mostly just an illusion.

4 KB Random Reads

Turbo Write obviously doesn't help with random reads, so the complicated situation from the previous page doesn't apply. Each drive lands where we'd expect. They all hit the 90,000 IOPS mark at a queue depth of 32 and achieve 10,000 IOPS at a queue depth of one.

Samsung specifically mentioned that it optimized performance for a single outstanding command, and those efforts show. The fact that Samsung is seeing these read speeds and using triple-level-cell NAND is going to make a few competitors green with envy.

Samsung's newest efforts are eclipsed by a small cadre of performance-oriented SSDs, but by slim and frankly inconsequential margins. The 840 EVOs are faster than the 512 GB 830 and both 840s.

We look to maximum 4 KB read speeds for additional perspective. Some separation does occur, but again it's not particularly significant. It doesn't take much flash to achieve spectacular read performance, so we'll need to move on to writes for a clearer picture of performance differentiation.