On Sun, May 8, 2011 at 1:21 PM, guy keren <c...@actcom.co.il> wrote: > On Sun, 2011-05-08 at 12:26 +0300, shimi wrote: > > On Sun, May 8, 2011 at 12:01 PM, guy keren <c...@actcom.co.il> wrote: > > > > do you have the ability to extract wear leveling information > > from your > > SSD? it would be interesting to know whether the drive is > > being used in > > a manner that will indeed comply with the life-time expentency > > it is > > sold with (5 years?), or better, or worse. > > > > > > I don't know, how do you extract such information? > > > > The rated MTBF of my specific drive is 2 million hours. If I still > > know my math, that's some 228 years.... > > > > -- Shimi > > wear leveling has nothing to do with MTBF. once you write ~100,000 times > to a single cell in the SSD - it's dead. due to the wear leveling > methods of the SSD - this will happen once you write ~100,000 times to > all cell groups on the SSD - assuming the wear-leveling algorithm of the > SSD is implemented without glitches. > > I know... I was referring more to the "life time expectancy it is sold with" when I quoted that number. Unless block write fails do not consist of "a failure", and if not, I don't know what is, in an SSD :).
Obviously on a DB data disk it is going to happen much faster than on my desktop. b.t.w. IIRC when a cell dies, it does so "gracefully"; I.e. no data is lost, and there are spare blocks for that case... and even when they're all full, you just get to the point that you still have your data read-only. I vaguely remember I read that somewhere... and if it's indeed like that, this is still way better than a regular hard drive - those tend to usually take all your data with them, and are much more sensitive to many things (shock - physical/electric, heat, etc...) > note that these writes don't come only from the host - many of them are > generated internally by the SSD, due to its wear-leveling algorithms. an > SSD could perform several writes for each host-initiated write operation > on average. intel claims their X25-E has very impressive algorithms in > this regard. it'll be interesting to check these claims with the actual > state of your SSD. > > I know that too :) > > fetching wear-leveling info is SSD-dependent. you'll need to check if > intel provides a tool to do that on linux, for your SSD. > > Google didn't help me a lot in that regard (I understand there's a Win$ SW maybe to do that; "Unfortunately", I don't have code from Redmond anywhere inside my chassis.) So if you find something yourself, I'm willing to test... -- Shimi
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