We just concluded a busy few days at the fall Storage Networking World in Dallas. Not surprisingly, a lot of the discussions centered on doing more with less. Nearly everyone is interested in what SSDs could do for their enterprise, but they’re cautious too, and not sure they know enough about this new technology to choose the best SSD for their application. So how do you know which SSD will work best for you? Unfortunately, it’s not such a simple question. All SSDs are not created equal, and you can’t rely solely on the quoted specs to tell them apart. If you do that, you’re setting yourself up for disappointment. Quoted specs are typically based on fresh-out-of-box (FOB) performance—the best performance the drive will ever achieve. Instead, you should look at steady state performance—the level the drive achieves once it fills to the point where write performance varies little over a relatively long period. Often, it’s at a significantly different level than the FOB performance numbers.
Why the difference? As the drive begins to fill, performance is impacted by a SSD phenomenon called write amplification—a multiplying effect that results from having to rewrite user data on the SSD. Inefficient garbage collection and wear leveling algorithms can further increase the write amplification of a SSD. You can compare the steady-state performance differences between our enterprise P300 drive and competitors in the benchmarks we posted back in August. Steady state performance is an important matter that deserves more attention and education. That’s why one of my colleagues devoted much of his time here at SNW to conduct a hands-on lab that demonstrated how to set up an Iometer test that showed significant differences between the steady-state results of client and enterprise SSDs. We believe that the more people know about the specifics of SSD performance, the better the likelihood that they’ll make an educated choice and be pleased with the results they get. We’re working on a whitepaper that explains more about the technical details behind SSD performance states.
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