Wear-levelling: adding to the slowdown
Wear-levelling: adding to the slowdownThen there's the unavoidable issue of wear-levelling, required by SSDs to mitigate the problems associated with, literally, wearing out the NAND flash. MLC-based drives generally tend to ship with ICs that can be written to around 10,000 times before terminal failure sets in. Advanced algorithms keep a track of what's written and where to, ensuring that no cells are used significantly more than others during read/write operations. A problem of such an approach is that, over time, fragmentation inevitably takes place and slows the drive down. A secure-erase command will sort out the problem at the cost of removing and writing data. However, SSD manufacturers have now begun releasing tools that combat the problem by defragging the drive without losing data.
The point is that SSDs aren't ideal. The architecture is such that you have to write more than you really need to, and MLC-based drives' longevity isn't great. Couple the two together and there's potential for a shorter-than-expected time before failure allied to slower speeds. Great! SLC-based drives do better in this regard, having much higher write endurance, but at the clear cost of a much higher etail price.
Got through all that? Your SSD still might not perform as expected in certain scenarios requiring concurrent reads and writes unless the controller and firmware have been optimised. Phew!
Nascent SSD technology has a long way to go before these 'bugs' are ironed out. Our advice would be to look beyond just the quoted sustained read/write figures and see what support the SSD manufacuter provides. With that out of the way, let's hit take a look at the Corsair drive.
