Has your computer ever become unresponsive, sometimes for as long as a second or two?
While doing my homework designing a new PC I came across the subject of "max latency", particularly as it relates to SSDs. The nature of SSDs demands that the controller has to do a deal of housekeeping to keep performance at a reasonable level. Here's a graph of maximum write latency for a number of drives:
It is from this review
of the Samsung SM843 Enterprise SSD over at StorageReview.com and I urge you to follow the link, not only to support the site but also to get the full background. My current Samsung PB22-J 256GB drive is four years old, a strong unit in its day but I have my suspicions that its max latency is up there with the worst of the drives in the graph above!
The max latency of some of the first generation SSDs is pretty shocking but even today's gold standard consumer drive, the Samsung 840 Pro, can occasionally post a 3/4 second latency if you catch it at a bad moment!
If you look at the average write latency then things seem a lot rosier:
These are the sort of numbers you see on the typical sales blurb and, comparing the two charts, one can see that they can hide a significant issue. It might come as no surprise to know that I am strongly considering the Intel DC S3700 for my next build. It's horribly expensive and it doesn't necessarily offer the best read throughput but it performs consistently and as I expect the new machine to still be in use ten years from now (CPU performance has plateau-ed IMHO) I can amortise the cost over that period and still be confident that the drive is well inside its design life and performing strongly.