On Oct 27, 2013, at 5:57 PM, Christoph Anton Mitterer <calestyo@xxxxxxxxxxxx> wrote: > On Sun, 2013-10-27 at 15:15 -0400, J. Bruce Fields wrote: >> Was this problem actually caught using checksums stored in xattrs, or >> did the problem predate your use of xattrs? > Phew... don't remember actually... but I think I haven't used that > already back then and noticed it by chance when I did some diffs. > > >>> So the idea of my integrity data is, that I really manually say "now the >>> data is in the state where I consider it to be consistent and I want to >>> have checksums stored and attached to the files, for exactly that >>> state", e.g. after I have read out some images from the SD card (perhaps >>> even twice with the cache cleared and the results diffed) and placed in >>> my archive. >>> Afterwards I can regularly verify the whole archive and if at some stage >>> corruptions as the above would have happened, I can simply take the >>> respective files from backups. >> How long have you been using this for? > Uhm... about 3-4 years now. > >> How many problems has it caught? > I do not keep exact statistics... but I remember a few cases where I > found damaged backups (optimal media) which I replaced as a consequence. > >> How often do you checksum or verify files, and how expensive is that? > Not that often,... on my actual data disks,... about every 4 months... > on my backup media (I use to keep older generations of backups as well) > about once a year. > > I've never really looked at how expensive it is,... all you need to do > is simply reading all data + have their hashes calculated. ...and if the checksums are any good, then all you need to do to substitute a database is to realise that a good data checksum is invariant under renames. -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
