“It’s a fairly well known fact that solid-state disk (SSD) performance can suffer over time. This was quite common in early SSDs, but newer controllers have helped reduce this problem through a variety of techniques. In part one of this two-part look at SSDs, we examine the origins of the performance problems and some potential solutions.”
That’s how Enterprise Storage Forum contributor Jeffrey Layton begins his exhaustive two-part series on SSD performance degradation.
For years (decades, actually), the focus on SSDs was on the exorbitant prices of the devices. Then the attention shifted to reliability, or endurance, issues. But SSD and controller manufacturers made great strides in those areas over the past couple years.
Now, the focus may be turning to performance degradation over time.
Layton’s articles are the best I’ve read on this subject. However, a warning: The articles are very long, very technical, and very detailed. But if you (a) are using, or considering using, SSDs (b) have sufficient technical credentials and (c) have a lot of time, I strongly recommend reading the articles.
Part 1 examines the issues that cause performance degradation in SSDs, and looks at some of the solutions (or “workarounds,” because all SSD solutions seem to involve trade-offs) that vendors have implemented.
Part 2 looks at technologies/issues such as write amplification, over-provisioning and the TRIM command, and then delves into some very in-depth testing of Intel’s X25-E SSD in ‘before’ and ‘after’ stress test scenarios.