On Tue, Mar 22, 2016 at 9:19 PM, John Marrett <jo...@zioncluster.ca> wrote: > I recently had a drive failure in a file server running btrfs. The > failed drive was completely non-functional. I added a new drive to the
I asume you did btrfs device add ? Or did you do this with btrfs replace ? > filesystem successfully, when I attempted to remove the failed drive I > encountered an error. I discovered that I actually experienced a dual > drive failure, the second drive only exhibited as failed when btrfs > tried to write to the drives in the filesystem when I removed the > disk. > > I shut down the array and imaged the failed drive using GNU ddrescue, > I was able to recover all but a few kb from the drive. Unfortunately, > when I imaged the drive I overwrote the drive that I had successfully > added to the filesystem. > > This brings me to my current state, I now have two devices missing: > > - the completely failed drive > - the empty drive that I overwrote with the second failed disks image > > Consequently I can't start the filesystem. I've discussed the issue in > the past with Ke and other people on the #btrfs channel, the > concensus; as I understood it, is that with the right patch it should > be possible to mount either the array with the empty drive absent or > to create a new btrfs fileystem on an empty drive and then manipulate > its UUIDs so that it believes it's the missing UUID from the existing > btrfs filesystem. > > Here's the info showing the current state of the filesystem: > > ubuntu@ubuntu:~$ sudo btrfs filesystem show > warning, device 6 is missing > warning devid 6 not found already > warning devid 7 not found already > Label: none uuid: 67b4821f-16e0-436d-b521-e4ab2c7d3ab7 > Total devices 7 FS bytes used 5.47TiB > devid 1 size 1.81TiB used 1.71TiB path /dev/sda3 > devid 2 size 1.81TiB used 1.71TiB path /dev/sdb3 > devid 3 size 1.82TiB used 1.72TiB path /dev/sdc1 > devid 4 size 1.82TiB used 1.72TiB path /dev/sdd1 > devid 5 size 2.73TiB used 2.62TiB path /dev/sde1 > *** Some devices missing > btrfs-progs v4.0 The used kernel version might also give people some hints. Also, you have not stated what raid type the fs is; likely not raid6, but rather raid 1 or 10 or 5 btrfs filesystem usage will report and show this. If it is raid6, you could still fix the issue in theory. AFAIK there are no patches to fix a dual error in case it is other raid type or single. The only option is then to use btrfs rescue on the umounted array and hope to copy as much as possible off the damaged fs to other storage. > ubuntu@ubuntu:~$ sudo mount -o degraded /dev/sda3 /mnt > mount: wrong fs type, bad option, bad superblock on /dev/sda3, > missing codepage or helper program, or other error > > In some cases useful info is found in syslog - try > dmesg | tail or so. > ubuntu@ubuntu:~$ dmesg > [...] > [ 749.322385] BTRFS info (device sde1): allowing degraded mounts > [ 749.322404] BTRFS info (device sde1): disk space caching is enabled > [ 749.323571] BTRFS warning (device sde1): devid 6 uuid > f41bcb72-e88a-432f-9961-01307ec291a9 is missing > [ 749.335543] BTRFS warning (device sde1): devid 7 uuid > 17f8e02a-923e-4ac3-9db2-eb1b47c1a8db missing > [ 749.407802] BTRFS: bdev (null) errs: wr 81791613, rd 57814378, > flush 0, corrupt 0, gen 0 > [ 749.407808] BTRFS: bdev /dev/sde1 errs: wr 0, rd 5002, flush 0, > corrupt 0, gen 0 > [ 774.759717] BTRFS: too many missing devices, writeable mount is not allowed > [ 774.804053] BTRFS: open_ctree failed > > Thank you in advance for your help, > > -JohnF > -- > To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in > the body of a message to majord...@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
