On Sun, 30 May 2010 14:20:36 +0000 (UTC) Grant Edwards wrote: > On 2010-05-30, Neil Bothwick <n...@digimed.co.uk> wrote: > > On Sat, 29 May 2010 07:59:31 -0400, David Relson wrote: > > > >> Indeed flash drives _do_ have a lifetime. My recollection is that > >> it's in the thousands of writes if not the hundreds of thousands > >> of writes. Assuming a life of 1,000 writes and you backup once > >> daily, that's 3 years of backups. 10,000 writes would be 30 > >> years. Of course if you backup every hour, 10,000 writes is a > >> year (or so). > > > > You're assuming that each backup only writes once, which is far from > > true. If you mount a drive with the sync option, the FAT is updated > > for every block you write, so even a single file can cause > > thousands of writes to the same location. > > And you're assuming that the flash controller chip in the USB drive > doesn't do wear-leavelling.
FWIW, I have enabled synchronous writes for a Disk-On-Module (SSD) formatted ext2. It makes writing take significantly longer and I have had a DOM go bad (become unusable). Admittedly, I don't know whether the DOM does wear-levelling and I don't know the underlying cause of the failure. In any case it was "Not Good (tm)" ...
