SSD Write Endurance 25nm Vs 34nm

[johnw]

The Intel 320 40GB has 48GiB of NAND? Hmmm, that would put its WA at like 1.2x, which I find odd (being worse than the X25-V). Could that have been as a trade for speed compared to the X25-V? Does it really need 28.8% (37.27GiB usable on 48GiB NAND) spare area?

No, no, no!

The 40GB 320 does indeed have 48GiB of flash on its circuit board, that is a fact (no need for anyone to double-check unless you really want to), but you need to read what I wrote! Only 40GiB of the flash is used for normal operation. The extra 8GiB is used for XOR parity data. So WA should be calculated assuming 40GiB of flash.

That is similar to Sandforce SSDs where, for example, a 120GB Sandforce drive usually has 128GiB of flash on-board, but only 120GiB of the flash is used for normal operation (data storage and reserved space), while the extra 8GiB is used for so-called RAISE, which is Sandforce's name for RAID-4 like parity. Although I am less certain with Sandforce (as compared to Intel 320) how they actually implement RAISE. It could be RAID-5 like, as far as I know. But I'd guess RAID-4 like.