Feb 14 18:30:21 specialbrew kernel: [27576201.178630] BTRFS: bdev /dev/sdh
errs: wr 128, rd 8, flush 2, corrupt 0, gen 0
Feb 14 18:30:21 specialbrew kernel: [27576201.309583] BTRFS: lost page write
due to I/O error on /dev/sdh
Feb 14 18:30:21 specialbrew kernel: [27576201.315761] BTRFS: bdev /dev/sdh
errs: wr 129, rd 8, flush 2, corrupt 0, gen 0
Feb 14 18:30:21 specialbrew kernel: [27576201.322086] BTRFS: lost page write
due to I/O error on /dev/sdh
…and those BTRFS: messages continue now even though the system no
longer has a /dev/sdh.
You need the patch set
[PATCH 00/15] btrfs: Hot spare and Auto replace
which includes the patch required here.
[PATCH 07/15] btrfs: introduce device dynamic state transition to
offline or failed
and this will take care of stopping the IO when disk fails.
Now:
$ sudo btrfs fi sh /srv/tank
Label: 'tank' uuid: 472ee2b3-4dc3-4fc1-80bc-5ba967069ceb
Total devices 6 FS bytes used 1.57TiB
devid 3 size 1.82TiB used 383.00GiB path /dev/sdg
devid 4 size 1.82TiB used 384.00GiB path /dev/sdf
devid 5 size 2.73TiB used 1.25TiB path /dev/sdk
devid 6 size 1.82TiB used 347.00GiB path /dev/sdj
devid 7 size 2.73TiB used 464.00GiB path /dev/sde
*** Some devices missing
btrfs progs has a code to fabricate missing in the user land
instead of obtaining from the kernel.
---
commit 206efb60cbe3049e0d44c6da3c1909aeee18f813
btrfs-progs: Add missing devices check for mounted btrfs.
---
So I recommend to use 'btrfs fi show -m', which I guess in your
case shall not show that devid 2 is missing. Because without
the kernel patch
[PATCH 07/15] btrfs: introduce device dynamic state transition to
offline or failed
Kernel won't make that (online to offline/failed) transitions at all.
Current workaround to tell kernel that a device is missing is only
by .. unmount and mount (not remount (bug)) which is a kind of
(enterprise unacceptable) workaround. Sorry about that.
$ sudo btrfs dev usage /srv/tank
::
/dev/sdh, ID: 2
Device size: 0.00B
Data,RAID1: 383.00GiB
Metadata,RAID1: 1.00GiB
System,RAID1: 32.00MiB
Unallocated: 1.44TiB
Yep kernel does not know that device is missing. That
part of the code is in the patch to be integrated as above.
So, ideally I'd like to remove the missing device sdh (id 2) to have
redundant copies of the data until I can insert a new drive. But
"remove" doesn't seem to want to work:
$ sudo btrfs dev remove /dev/sdh /srv/tank
ERROR: not a block device: /dev/sdh
$ sudo btrfs dev remove 2 /srv/tank
ERROR: not a block device: 2
$ btrfs --version
btrfs-progs v4.4
Since now device is removed. So only option is to use devid
if you want to remove/delete. but it needs the patch.
[PATCH 0/7] Introduce device delete by devid
I think this is being integrated into 4.5.x (needs both kernel
and progs patches).
If you happen to try any of these patches, please consider to
post results.
I expect my kernel might be too old as it is a Debian backports
version on wheezy (linux-image-3.16.0-0.bpo.4-amd64
3.16.7-ckt20-1+deb8u3~bpo70+1).
If I upgrade the kernel then should one of those remove commands
above work?
I would rather not reboot just now if I can achieve redundancy in
some other way. Would a rebalance like:
$ sudo btrfs balance -f -v -sdevid=2 -mdevid=2 /srv/tank
reconstruct redundant copies elsewhere?
No. Please don't do that. It would aggravate the IO errors and
disk will never be removed from the kernel.
I suggest reboot if its btrfs root or btrfs is not a kernel module,
otherwise
umount
modprobe -r btrfs (removes stale device entries)
btrfs dev scan
mount
Now 'btrfs fi show -m' should show device id 2 missing.
So now either you may replace devid2 or delete devid 2 based
on your business data protection needs.
Kindly note. If you are trying the hot spare and auto replace patches,
in this context after the reboot, the device id will be identified
as missing. And Not failed. So the auto replace won't trigger
the replace if you have a spare device. This is as designed.
With this btrfs-progs and kernel version, will a later "btrfs
replace start -r /dev/sdh /dev/sdl" work without me rebooting into a
newer kernel, even though /dev/sdh doesn't exist as a device to the
kernel right now?
Yes you can consider this, without needing to reboot, however the
command will be
btrfs replace start -r 2 /dev/sdl /btrfs
Thanks, Anand
Any information/advice appreciated.
Cheers,
Andy
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