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Results: 4 KB Random Performance

OCZ Vector 150 SSD Review: A New Flagship With 19 nm Flash
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We turn to Iometer as our synthetic metric of choice for testing 4 KB random performance. 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 it, so the idea that the operating system sees one piece of information next to another is mostly just an illusion.

4 KB Random Reads

Testing the performance of SSDs often emphasizes 4 KB random reads, and for good reason. Most system accesses are both small and random. Moreover, read performance is arguably more important than writes when you're talking about typical client workloads.

The original Vector hits the magic 100,000 IOPS threshold. The Vertex 450 and Vector 150 can't quite get there, falling just south of 90,000. Maximum numbers are found in the chart below, but this is clearly the older Vector's ballgame. The newer Vector 150 just doesn't achieve quite the same performance level at high queue depths. Granted, at the lower queue depths most desktop tasks push, the results are fundamentally identical.

4 KB Random Writes

Random write performance is also important. Early SSDs didn't do well in this discipline, seizing up even in light workloads. Newer SSDs wield more than 100x the performance of drives from 2007, though we also recognize that there's a point of diminishing returns in desktop environments.

When you swap a hard drive out for solid-state storage, your experience improves. Load times, boot times, and system responsiveness all get better. When it's called upon, your SSD can handle a lot more I/O than the spinning media you had in there before. When it comes to typical client workloads however, getting to those operations faster is what matters, not necessarily trying to juggle more of them.

In our testing, all three OCZ SSDs level off after 90,000 IOPS. But performance at lower queue depths is, again, excellent.

Here's a break-down of the maximum observed 4 KB sequential read and write performance with Iometer. The order the drives appear in our chart is determined by maximum combined read and write performance.

In retrospect, the original Vector doesn't get enough credit for its speed. It achieves a first-place finish, edging out the powerful 840 Pro. OCZ's Vector 150 slots in a couple of spots lower, while Vertex 450 falls in a few spots below that. This is a trend you'll see again before this review is over. In essence, the Vector 150 falls in between the original Vector and older Vertex 450.

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