All good in SSD Eden? MLC vs. SLC
All good in SSD Eden?Solid-state drives appear to be the perfect upgrade for the user looking for a jump in performance. Blistering sequential read/write speed and hideously-fast random operations, due to a lack of moving parts, mean that they should trounce traditional mechanical-based drives in access-intensive work patterns. The truth is that SSDs do have an Achilles Heel, and it's caused by how the memories on the drive interface with the system.
An SSD will ship with either flash (NAND) or DRAM chips, with the former being far more prevalent in the drives of today. Taking the volume-selling drives into account, flash ICs are mounted on to a PCB and interface with multi-channel controllers that leverage the cumulative speed from the ICs, delivering it to the system. Add a number of high-quality ICs and, say, a 10-channel controller, and this is how, in part, SSDs can hit well over 200MB/s sustained read and write speeds.
MLC vs. SLC
The majority of desktop/consumer flash-based SSDs ship with MLC (multi-level cell) memory where (at least) two bits of information are stored in each cell. SLC (single-level cell), on the other hand, stores just a single bit per cell. Simple math tells us that MLC memory's density - more bits per cell - make it cheaper to produce, but at the cost of overall performance (longer write times) and lower longevity - MLC-based drives have significantly lower write endurance than SLCs because of the access taking place.
