This is needed to prevent any inconsistencies stemming from buffered writes/caching file data during live VM migration. Besides, for Gluster to truly honor direct-io behavior in qemu's 'cache=none' mode (which is what oVirt uses), one needs to turn on performance.strict-o-direct and disable remote-dio.
-Krutika On Wed, Mar 27, 2019 at 12:24 PM Leo David <leoa...@gmail.com> wrote: > Hi, > I can confirm that after setting these two options, I haven't encountered > disk corruptions anymore. > The downside, is that at least for me it had a pretty big impact on > performance. > The iops really went down - performing inside vm fio tests. > > On Wed, Mar 27, 2019, 07:03 Krutika Dhananjay <kdhan...@redhat.com> wrote: > >> 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 <san...@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 <san...@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 >>> _______________________________________________ >>> Users mailing list -- us...@ovirt.org >>> To unsubscribe send an email to users-le...@ovirt.org >>> Privacy Statement: https://www.ovirt.org/site/privacy-policy/ >>> oVirt Code of Conduct: >>> https://www.ovirt.org/community/about/community-guidelines/ >>> List Archives: >>> https://lists.ovirt.org/archives/list/us...@ovirt.org/message/M3T2VGGGV6DE643ZKKJUAF274VSWTJFH/ >>> >> _______________________________________________ >> Users mailing list -- us...@ovirt.org >> To unsubscribe send an email to users-le...@ovirt.org >> Privacy Statement: https://www.ovirt.org/site/privacy-policy/ >> oVirt Code of Conduct: >> https://www.ovirt.org/community/about/community-guidelines/ >> List Archives: >> https://lists.ovirt.org/archives/list/us...@ovirt.org/message/ZUIRM5PT4Y4USOSDGSUEP3YEE23LE4WG/ >> >
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