Finally,. SSDs just die over time. Especially if they are not powered on and refreshing. JEDEC specs say that they should retain data for 1 year unplugged when stored at 30 degrees celsius, assuming the internet isn't lying to me.
Keep backups. Quoth Dave Eckhardt <davide...@cs.cmu.edu>: > > For the napkin calculation: On disk, the IEntry is 38Bytes. Alas, > > writes occur always in (the ssd internal) blocksize. So, essentially > > (assuming 4096 byte blocksize, which is quite optimistic), we have > > a write efficiency of less than 1 percent. > > While I see how such a model can predict disaster, I don't think that > model matches how FTLs work, because it can't. > > Many file systems (FAT, ext2/3/4) write the same logical block over > and over and over and over and over. I think the default interval > for ext4 to synch the superblock and the journal is five seconds, > which if true is more than 15,000 times every *day* for a busy > file system (and I think lots of Linux systems are busy in that > sense). > > > A good firmware in the ssd could avoid needing a new block for the > > write, if all bits are changed in teh same direction by the new > > data. > > Again, I believe this model predicts that no regular Linux file > system can be used on any SSD, thus I believe this model is not > accurate. > > To quote Wikipedia: > > https://en.wikipedia.org/wiki/Flash_memory_controller > > > The mapping units of an FTL can differ so that LBAs are mapped > > block-, page- or even sub-page-based. Depending on the usage > > pattern, a finer mapping granularity can significantly reduce > > the flash wear out and maximize the endurance of a flash based > > storage media. > > Also, I feel as if this point is several assumption layers deep. > I think one user reported an unknown number of failures in two > sets of SSDs of unknown brand and model. I don't think we know > that it was venti SSDs that went bad as opposed to fossil SSDs, > let alone knowing it was index SSDs for venti. > > > It seems, venti in its current form is a ssd killer, if they > > are used for the isects. > > I don't think this claim is yet supported well. > > Dave Eckhardt ------------------------------------------ 9fans: 9fans Permalink: https://9fans.topicbox.com/groups/9fans/T2ca67486c7a13a77-M076297816c8a30d15e67368f Delivery options: https://9fans.topicbox.com/groups/9fans/subscription
