If you can mount it RO, first thing to do is back up any data that you care about. According to the bug that Omar posted you should not try a device replace and you should not try a scrub with a missing device. You may be able to just do a device delete missing, then separately do a device add of a new drive, or rebalance back in to raid1. On Mon, Jul 6, 2015 at 4:12 PM, Hendrik Friedel <hendrik@xxxxxxxxxxxxx> wrote: > Hello, > > oh dear, I fear I am in trouble: > recovery-mounted, I tried to save some data, but the system hung. > So I re-booted and sdc is now physically disconnected. > > Label: none uuid: b4a6cce6-dc9c-4a13-80a4-ed6bc5b40bb8 > Total devices 3 FS bytes used 4.67TiB > devid 1 size 2.73TiB used 2.67TiB path /dev/sdc > devid 2 size 2.73TiB used 2.67TiB path /dev/sdb > *** Some devices missing > > I try to mount the rest again: > mount -o recovery,ro /dev/sdb /mnt/__Complete_Disk > mount: wrong fs type, bad option, bad superblock on /dev/sdb, > missing codepage or helper program, or other error > In some cases useful info is found in syslog - try > dmesg | tail or so > > root@homeserver:~# dmesg | tail > [ 447.059275] BTRFS info (device sdc): enabling auto recovery > [ 447.059280] BTRFS info (device sdc): disk space caching is enabled > [ 447.086844] BTRFS: failed to read chunk tree on sdc > [ 447.110588] BTRFS: open_ctree failed > [ 474.496778] BTRFS info (device sdc): enabling auto recovery > [ 474.496781] BTRFS info (device sdc): disk space caching is enabled > [ 474.519005] BTRFS: failed to read chunk tree on sdc > [ 474.540627] BTRFS: open_ctree failed > > > mount -o degraded,ro /dev/sdb /mnt/__Complete_Disk > Does work now though. > > So, how can I remove the reference to the failed disk and check the data for > consistency (scrub I suppose, but is it safe?)? > > Regards, > Hendrik > > > > > On 06.07.2015 22:52, Omar Sandoval wrote: >> >> On 07/06/2015 01:01 PM, Donald Pearson wrote: >>> >>> Based on my experience Hugo's advice is critical, get the bad drive >>> out of the pool when in raid56 and do not try to replace or delete it >>> while it's still attached and recognized. >>> >>> If you add a new device, mount degraded and rebalance. If you don't, >>> mount degraded then device delete missing. >>> >> >> Watch out, replacing a missing device in RAID 5/6 currently doesn't work >> and will cause a kernel BUG(). See my patch series here: >> http://www.spinics.net/lists/linux-btrfs/msg44874.html >> > > > -- > Hendrik Friedel > Auf dem Brink 12 > 28844 Weyhe > Tel. 04203 8394854 > Mobil 0178 1874363 > > > --- > Diese E-Mail wurde von Avast Antivirus-Software auf Viren geprüft. > https://www.avast.com/antivirus > -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
