[linux-lvm] Unsync-ed LVM Mirror

[Eric Ren]

Hi,

Your LVM version and kernel version please?

like:
""""
# lvm version
   LVM version:     2.02.177(2) (2017-12-18)
   Library version: 1.03.01 (2017-12-18)
   Driver version:  4.35.0

# uname -a
Linux sle15-c1-n1 4.12.14-9.1-default #1 SMP Fri Jan 19 09:13:51 UTC 
2018 (849a2fe) x86_64 x86_64 x86_64 GNU/Linux
"""

Eric

On 02/03/2018 05:43 PM, Liwei wrote:
> Hi list,
>      I had a LV that I was converting from linear to mirrored (not
> raid1) whose source device failed partway-through during the initial
> sync.
>
>      I've since recovered the source device, but it seems like the
> mirror is still acting as if some blocks are not readable? I'm getting
> this in my logs, and the FS is full of errors:
>
> [  +1.613126] device-mapper: raid1: Unable to read primary mirror
> during recovery
> [  +0.000278] device-mapper: raid1: Primary mirror (253:25) failed
> while out-of-sync: Reads may fail.
> [  +0.085916] device-mapper: raid1: Mirror read failed.
> [  +0.196562] device-mapper: raid1: Mirror read failed.
> [  +0.000237] Buffer I/O error on dev dm-27, logical block 5371800560,
> async page read
> [  +0.592135] device-mapper: raid1: Unable to read primary mirror
> during recovery
> [  +0.082882] device-mapper: raid1: Unable to read primary mirror
> during recovery
> [  +0.246945] device-mapper: raid1: Unable to read primary mirror
> during recovery
> [  +0.107374] device-mapper: raid1: Unable to read primary mirror
> during recovery
> [  +0.083344] device-mapper: raid1: Unable to read primary mirror
> during recovery
> [  +0.114949] device-mapper: raid1: Unable to read primary mirror
> during recovery
> [  +0.085056] device-mapper: raid1: Unable to read primary mirror
> during recovery
> [  +0.203929] device-mapper: raid1: Unable to read primary mirror
> during recovery
> [  +0.157953] device-mapper: raid1: Unable to read primary mirror
> during recovery
> [  +3.065247] recovery_complete: 23 callbacks suppressed
> [  +0.000001] device-mapper: raid1: Unable to read primary mirror
> during recovery
> [  +0.128064] device-mapper: raid1: Unable to read primary mirror
> during recovery
> [  +0.103100] device-mapper: raid1: Unable to read primary mirror
> during recovery
> [  +0.107827] device-mapper: raid1: Unable to read primary mirror
> during recovery
> [  +0.140871] device-mapper: raid1: Unable to read primary mirror
> during recovery
> [  +0.132844] device-mapper: raid1: Unable to read primary mirror
> during recovery
> [  +0.124698] device-mapper: raid1: Unable to read primary mirror
> during recovery
> [  +0.138502] device-mapper: raid1: Unable to read primary mirror
> during recovery
> [  +0.117827] device-mapper: raid1: Unable to read primary mirror
> during recovery
> [  +0.125705] device-mapper: raid1: Unable to read primary mirror
> during recovery
> [Feb 3 17:09] device-mapper: raid1: Mirror read failed.
> [  +0.167553] device-mapper: raid1: Mirror read failed.
> [  +0.000268] Buffer I/O error on dev dm-27, logical block 5367765816,
> async page read
> [  +0.135138] device-mapper: raid1: Mirror read failed.
> [  +0.000238] Buffer I/O error on dev dm-27, logical block 5367765816,
> async page read
> [  +0.000365] device-mapper: raid1: Mirror read failed.
> [  +0.000315] device-mapper: raid1: Mirror read failed.
> [  +0.000213] Buffer I/O error on dev dm-27, logical block 5367896888,
> async page read
> [  +0.000276] device-mapper: raid1: Mirror read failed.
> [  +0.000199] Buffer I/O error on dev dm-27, logical block 5367765816,
> async page read
>
>      However, if I take down the destination device and restart the LV
> with --activateoption partial, I can read my data and everything
> checks out.
>
>      My theory (and what I observed) is that lvm continued the initial
> sync even after the source drive stopped responding, and has now
> mapped the blocks that it 'synced' as dead. How can I make lvm retry
> those blocks again?
>
>      In fact, I don't trust the mirror anymore, is there a way I can
> conduct a scrub of the mirror after the initial sync is done? I read
> about --syncaction check, but seems like it only notes the number of
> inconsistencies. Can I have lvm re-mirror the inconsistencies from the
> source to destination device? I trust the source device because we ran
> a btrfs scrub on it and it reported that all checksums are valid.
>
>      It took months for the mirror sync to get to this stage (actually,
> why does it take months to mirror 20TB?), I don't want to start it all
> over again.
>
> Warm regards,
> Liwei
>
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