I think I've finally nailed down a test case, if anyone is bored and wants to play: https://bugs.launchpad.net/ubuntu/+source/lvm2/+bug/1814389 I can't file upstream as RH bugzilla is down at the moment.. S. On Sat, 2 Feb 2019 at 13:34, Steve Dodd wrote: > Weirdly, I thought I had failed to reproduce this bug, but my auto-scrub > job ran this morning (first Sat of month), and I got: > > 03:15:15: Starting scrub of rvg/test ... > 03:15:15: ... scrub started ... > 03:18:36: FAILED: 7926656 mismatches > > So I really have no idea what's going on there. I will wade through my > bash history and see if I can see what I did last week and what triggered > this.. > > S. > > On Wed, 23 Jan 2019 at 10:46, Steve Dodd wrote: > >> 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 >> >