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From: Steve Dodd <steved424@gmail.com>
To: linux-lvm@redhat.com
Subject: Re: [linux-lvm] Scrub errors after extending LVM RAID1 mirror [full email]
Date: Wed, 23 Jan 2019 10:46:29 +0000	[thread overview]
Message-ID: <CAJ6XMjFuj4acAq3Fahj7wd7Kbyh09Geq4Pt9UVwQYDf1Th9S=g@mail.gmail.com> (raw)
In-Reply-To: <CAJ6XMjEzDgj4iccGVKkWftBWNiQbnRkPOKnOCrgSLjhzdm+Z=A@mail.gmail.com>

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Sorry, user error sent the last email before I'd finished typing, trying
again..

Hi everyone,

I am experiencing a mystery scrub failure after extending a particular LV
which is a raid1 type mirror. I am using Ubuntu 18.04, LVM
2.02.176-4.1ubuntu3, Ubuntu kernel 4.15.0-29-generic. I mentioned this on
IRC, thought an email might reach more people and allow me to provide more
detail.

As far as I can tell, the LV was *not* created with --nosync:

# lvs rvg/backups
>   LV      VG  Attr       LSize  Pool Origin Data%  Meta%  Move Log
> Cpy%Sync Convert
>   backups rvg rwi-aor--- 96.64G                                    100.00
>


The only odd thing I tend to do is specify extents for the extension
manually, being a bit OCD about on disk segment layouts. Having mined
.bash_history, it seems that last time I ran:

lvextend -l+2561 rvg/backups /dev/sdc3:20480-23041 /dev/sdb3:80097-82658


After that, a *lvchange --syncaction check rvg/backups* showed a huge
number for raid_mismatch_count (seemed roughly consistent with the newly
extended portion not being synced), but dumping the actual filesystem with
partclone from both legs of the mirror through md5sum showed no
inconsistencies; the contents are mostly borg repositories and for good
measure I verified the data in those using borg as well - no problems.

After a full resync all is well again. This is the second time this
happened to me on the same LV (I think - certainly the same VG.)

Any clues? Any known bugs fixed recently that might not have made it into
Ubuntu 1804? I am trying to reproduce with a test LV but can't. Only other
thing I can think might be relevant was that the volume was mounted (but
quiescent) at the time.

Thanks,
Steve

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  reply	other threads:[~2019-01-23 10:46 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-01-23 10:34 [linux-lvm] Scrub errors after extending LVM RAID1 mirror Steve Dodd
2019-01-23 10:46 ` Steve Dodd [this message]
2019-02-02 13:34   ` [linux-lvm] Scrub errors after extending LVM RAID1 mirror [full email] Steve Dodd
2019-02-02 16:09     ` Steve Dodd

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