On Fri, Feb 14, 2014 at 11:35:56AM +0100, Axelle wrote: > Hi, > I've just encountered a hard disk crash in one of my btrfs pools. > > sudo btrfs filesystem show > failed to open /dev/sr0: No medium found > Label: none uuid: 545e95c6-d347-4a8c-8a49-38b9f9cb9add > Total devices 3 FS bytes used 112.70GB > devid 1 size 100.61GB used 89.26GB path /dev/sdc6 > devid 2 size 93.13GB used 84.00GB path /dev/sdc1 > *** Some devices missing > > The device which is missing is /dev/sdb. I have replaced it with a new > hard disk. How do I add it back to the volume and fix the device > missing? > The pool is expected to mount to /samples (it is not mounted yet). > > I tried this - which fails: > sudo btrfs device add /dev/sdb /samples > ERROR: error adding the device '/dev/sdb' - Inappropriate ioctl for device > > Why isn't this working?
Because it's not mounted. :) > I also tried this: > sudo mount -o recovery /dev/sdc1 /samples > mount: wrong fs type, bad option, bad superblock on /dev/sdc1, > missing codepage or helper program, or other error > In some cases useful info is found in syslog - try > dmesg | tail or so > same with /dev/sdc6 Close, but what you want here is: mount -o degraded /dev/sdc1 /samples not "recovery". That will tell the FS that there's a missing disk, and it should mount without complaining. If your data is not RAID-1 or RAID-10, then you will almost certainly have lost some data. At that point, since you've removed the dead disk, you can do: btrfs device delete missing /samples which forcibly removes the record of the missing device. Then you can add the new device: btrfs device add /dev/sdb /samples And finally balance to repair the RAID: btrfs balance start /samples It's worth noting that even if you have RAID-1 data and metadata, losing /dev/sdc in your current configuration is likely to cause severe data loss -- probably making the whole FS unrecoverable. This is because the FS sees /dev/sdc1 and /dev/sdc6 as independent devices, and will happily put both copies of a piece of RAID-1 data (or metadata) on /dev/sdc -- one on each of sdc1 and sdc6. I therefore wouldn't recommend running like that for very long. 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 --- All hope abandon, Ye who press Enter here. ---
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