On Tue, 23 Aug 2016 12:30:35 +0000 Malte Westerhoff <MWesterhoff@xxxxxxxxxxxxxxxxx> wrote: > parent transid verify failed on 7375567323136 wanted 52059 found 52045 > parent transid verify failed on 7375567323136 wanted 52059 found 52045 > Error: could not find btree root extent for root 12974 > > This is kernel 4.1.27 and btrfs-progs 4.1.2. We also tried the btrfs check --repair with btrfs-progs 4.7 with the same result. > > The partition with the problem is /dev/mapper/VGBIGRAID6-DATA1 > (The partition is an LVM logical volume that is on top of an md raid6.) > > Anything else that we can try in order to recover the volume? In my experience the last resort solution to this is to simply kill the problematic block with the "btrfs-corrupt-block" tool (compile from btrfs-progs source), then run "btrfs check --repair" again, and this time it should quite trivially set things right. See my success story about that: http://www.spinics.net/lists/linux-btrfs/msg53061.html and especially note the part about making COW snapshots of the entire block device (should be easier since you already run LVM), which will allow you to experiment while having an ability to undo. Some files will be lost or corrupted (likely only an extremely tiny portion, but not knowing which -- sucks), so ideally you should always have means to verify the integrity of user data on any FS. At least for those which change infrequently, e.g. media file libraries, always keep '*.sfv' files produced by the 'cfv' tool beside everything. Also something along the lines of cd /mnt/mydata && find > /somewhereelse/mydata-`date -Iseconds`.lst in crontab. Before starting you can also try checking what kind of data the problematic block contains, IIRC it would be (but not guaranteed to be helpful): btrfs-debug-tree -b 7375567323136 /dev/mapper/VGBIGRAID6-DATA1 -- With respect, Roman
Attachment:
pgpLrMcD5YdUY.pgp
Description: OpenPGP digital signature
