On Mon, Sep 02, 2013 at 11:41:12PM +0200, Rain Maker wrote: > Hello list, > > So, I ran a full scrub, and, luckily, it only found 6 csum errors > (these 6). The damage therefore seems to be contained in "just" 1 > file. > > Now, I removed the offending file. But is there something else I > should have done to recover the data in this file? Can it be > recovered?
No, and no. The data's failing a checksum, so it's basically broken. If you had a btrfs RAID-1 configuration, the FS would be able to recover from one broken copy using the other (good) copy. > I'm running 3.11-rc7. It is a single disk btrfs filesystem. I have > several subvolumes defined, one of which for VMWare Workstation (on > which the corruption took place). Aaah, the VM workload could explain this. There's some (known, won't-fix) issues with (I think) direct-IO in VM guests that can cause bad checksums to be written under some circumstances. I'm not 100% certain, but I _think_ that making your VM images nocow (create an empty file with touch; use chattr +C; extend the file to the right size) may help prevent these problems. > I checked the SMART values, they all seem OK. The harddisks in this > machine are less then a month old. I replaced them after seeing > similar messages on the "old" disks. > > Is the only logical explanation for this some kind of hardware failure > (SATA controller, power supply...), or could there be something more > to this? As above, there's some direct-IO problems with data changing in-flight that can lead to bad checksums. Fixing the issue would cause some fairly serious slow-downs in performance for that case, which is rather against what direct-IO is trying to do, so I think it's unlikely the behaviour will be changed. Of course, I could be completely wrong about all this, and you've got bad RAM or PSU something... Hugo. -- === Hugo Mills: hugo@... carfax.org.uk | darksatanic.net | lug.org.uk === PGP key: 65E74AC0 from wwwkeys.eu.pgp.net or http://www.carfax.org.uk --- "What are we going to do tonight?" "The same thing we do --- every night, Pinky. Try to take over the world!"
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