[Gluster-users] [ovirt-users] Re: VM disk corruption with LSM on Gluster

[Krutika Dhananjay]

Could you enable strict-o-direct and disable remote-dio on the src volume
as well, restart the vms on "old" and retry migration?

# gluster volume set <VOLNAME> performance.strict-o-direct on
# gluster volume set <VOLNAME> network.remote-dio off

-Krutika

On Tue, Mar 26, 2019 at 10:32 PM Sander Hoentjen <sander at hoentjen.eu> wrote:

> On 26-03-19 14:23, Sahina Bose wrote:
> > +Krutika Dhananjay and gluster ml
> >
> > On Tue, Mar 26, 2019 at 6:16 PM Sander Hoentjen <sander at hoentjen.eu>
> wrote:
> >> Hello,
> >>
> >> tl;dr We have disk corruption when doing live storage migration on oVirt
> >> 4.2 with gluster 3.12.15. Any idea why?
> >>
> >> We have a 3-node oVirt cluster that is both compute and gluster-storage.
> >> The manager runs on separate hardware. We are running out of space on
> >> this volume, so we added another Gluster volume that is bigger, put a
> >> storage domain on it and then we migrated VM's to it with LSM. After
> >> some time, we noticed that (some of) the migrated VM's had corrupted
> >> filesystems. After moving everything back with export-import to the old
> >> domain where possible, and recovering from backups where needed we set
> >> off to investigate this issue.
> >>
> >> We are now at the point where we can reproduce this issue within a day.
> >> What we have found so far:
> >> 1) The corruption occurs at the very end of the replication step, most
> >> probably between START and FINISH of diskReplicateFinish, before the
> >> START merge step
> >> 2) In the corrupted VM, at some place where data should be, this data is
> >> replaced by zero's. This can be file-contents or a directory-structure
> >> or whatever.
> >> 3) The source gluster volume has different settings then the destination
> >> (Mostly because the defaults were different at creation time):
> >>
> >> Setting                                 old(src)  new(dst)
> >> cluster.op-version                      30800     30800 (the same)
> >> cluster.max-op-version                  31202     31202 (the same)
> >> cluster.metadata-self-heal              off       on
> >> cluster.data-self-heal                  off       on
> >> cluster.entry-self-heal                 off       on
> >> performance.low-prio-threads            16        32
> >> performance.strict-o-direct             off       on
> >> network.ping-timeout                    42        30
> >> network.remote-dio                      enable    off
> >> transport.address-family                -         inet
> >> performance.stat-prefetch               off       on
> >> features.shard-block-size               512MB     64MB
> >> cluster.shd-max-threads                 1         8
> >> cluster.shd-wait-qlength                1024      10000
> >> cluster.locking-scheme                  full      granular
> >> cluster.granular-entry-heal             no        enable
> >>
> >> 4) To test, we migrate some VM's back and forth. The corruption does not
> >> occur every time. To this point it only occurs from old to new, but we
> >> don't have enough data-points to be sure about that.
> >>
> >> Anybody an idea what is causing the corruption? Is this the best list to
> >> ask, or should I ask on a Gluster list? I am not sure if this is oVirt
> >> specific or Gluster specific though.
> > Do you have logs from old and new gluster volumes? Any errors in the
> > new volume's fuse mount logs?
>
> Around the time of corruption I see the message:
> The message "I [MSGID: 133017] [shard.c:4941:shard_seek]
> 0-ZoneA_Gluster1-shard: seek called on
> 7fabc273-3d8a-4a49-8906-b8ccbea4a49f. [Operation not supported]" repeated
> 231 times between [2019-03-26 13:14:22.297333] and [2019-03-26
> 13:15:42.912170]
>
> I also see this message at other times, when I don't see the corruption
> occur, though.
>
> --
> Sander
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