On Mon, Sep 23, 2019 at 12:19 PM <hoegge@xxxxxxxxx> wrote: > > Dear BTRFS mailing list, > > I'm running BTRFS on my Synology Diskstation and they have referred me to > the BTRFS developers. If it's a generic question that's fine, but all the development happening on this list is very recent kernels and btrfs-progs, which is not typically the case with distribution specific products. > > For a while I have had quite a few (tens - not hundreds) checksum mismatch > errors on my device (around 6 TB data). It runs BTRFS on SHR (Synology > Hybrid Raid). Most of these checksum mismatches, though, do not seem "real". > Most of the files are identical to the original files (checked by binary > comparison and by recalculated MD5 hashes). > > What can explain that problem? I thought BTRFS only reported checksum > mismatch errors, when it cannot self-heal the files? It'll report them in any case, and also report if they're fixed. There are different checksum errors depending on whether metadata or data are affected (both are checksummed). Btrfs can only self-heal with redundant copies available. By default metadata is duplicated and should be able to self-heal, but data is not redundant by default. So it'd depend on how the storage stack layout is created. We need logs though. It's better to have more than less, if you can go back ~5 minutes from the first report of checksum mismatch error, that's better than too aggressive log trimming. Also possibly useful: # uname -a # btrfs --version -- Chris Murphy
