On 8 September 2015 at 21:34, Hugo Mills <h...@carfax.org.uk> wrote: > On Tue, Sep 08, 2015 at 09:18:05PM +0200, Ian Kumlien wrote: >> Hi, >> >> Currently i have a raid1 configuration on two disks where one of them >> is failing. >> >> But since: >> btrfs fi df /mnt/disk/ >> Data, RAID1: total=858.00GiB, used=638.16GiB >> Data, single: total=1.00GiB, used=256.00KiB >> System, RAID1: total=32.00MiB, used=132.00KiB >> Metadata, RAID1: total=4.00GiB, used=1.21GiB >> GlobalReserve, single: total=412.00MiB, used=0.00B >> >> There should be no problem in failing one disk... Or so i thought! >> >> btrfs dev delete /dev/sdb2 /mnt/disk/ >> ERROR: error removing the device '/dev/sdb2' - unable to go below two >> devices on raid1 > > dev delete is more like a reshaping operation in mdadm: it tries to > remove a device safely whilst retaining all of the redundancy > guarantees. You can't go down to one device with RAID-1 and still keep > the redundancy. > > dev delete is really for managed device removal under non-failure > conditions, not for error recovery. > >> And i can't issue rebalance either since it will tell me about errors >> until the failing disk dies. >> >> Whats even more interesting is that i can't mount just the working >> disk - ie if the other disk >> *has* failed and is inaccessible... though, i haven't tried physically >> removing it... > > Physically removing it is the way to go (or disabling it using echo > offline >/sys/block/sda/device/state). Once you've done that, you can > mount the degraded FS with -odegraded, then either add a new device > and balance to restore the RAID-1, or balance with > -{d,m}convert=single to drop the redundancy to single.
This did not work... [ 1742.368079] BTRFS info (device sda2): The free space cache file (280385028096) is invalid. skip it [ 1789.052403] BTRFS: open /dev/sdb2 failed [ 1789.064629] BTRFS info (device sda2): allowing degraded mounts [ 1789.064632] BTRFS info (device sda2): disk space caching is enabled [ 1789.092286] BTRFS: bdev /dev/sdb2 errs: wr 2036894, rd 2031380, flush 705, corrupt 0, gen 0 [ 1792.625275] BTRFS: too many missing devices, writeable mount is not allowed [ 1792.644407] BTRFS: open_ctree failed >> mdam has fail and remove, I assume for this reason - perhaps it's >> something that should be added? > > I think there should be a btrfs dev drop, which is the fail-like > operation: tell the FS that a device is useless, and should be dropped > from the array, so the FS doesn't keep trying to write to it. That's > not implemented yet, though. Damn it =) > Hugo. > > -- > Hugo Mills | Alert status mauve ocelot: Slight chance of > hugo@... carfax.org.uk | brimstone. Be prepared to make a nice cup of tea. > http://carfax.org.uk/ | > PGP: E2AB1DE4 | -- 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