I see. Then I will keep an eye on this tonight where we have a huge "all ovirt downtime" just to delete those snapshots ^^
Thanks and Cheers, Stefan On 10/27/14 13:07, Markus Stockhausen wrote: >> Von: Stefan Wendler [stefan.wend...@tngtech.com] >> Gesendet: Montag, 27. Oktober 2014 11:39 >> An: Markus Stockhausen >> Cc: users@ovirt.org >> Betreff: Re: [ovirt-users] Deleting large snapshots blocks the whole cluster >> >> Hi, >> >> do you mean during snapshot deletion or in general? >> >> In general we do not have any swap usage at all. On none of the 4 hosts. >> >> We had some swap I/O on the host that is SPM most of the time. But not >> during that period where we tried to delete the snapshot. >> > > I thought of the bug described in RH bugzilla 1138690 "[SCALE] snapshot > deletion -> > heavy swapping on SPM". In case you have no access to it (as it is RHEV > tagged): > > qemu-img reads through pagecache during snapshot deletion. A new flag has > been > intrduced in August this year that allows to avoid page cache. This flag must > be > provided by OVirt/RHEV. Target release is 3.6. > > Until then the only bugfix is to drop pagecache manually on regular intervals > on the > hypversior and especially the SPM node. > > Markus > >> >> Cheers, >> Stefan >> >> On 10/27/14 11:08, Markus Stockhausen wrote: >>> Do you see swapping on the SPM? If yes a regular echo 3 > drop_caches could >>> help. >>> >>> Markus >>> >>> Am 27.10.2014 10:57 schrieb Stefan Wendler <stefan.wend...@tngtech.com>: >>> Hi, >>> >>> we have some really large snapshots left from a migration. Since our >>> store is almost full now we have to delete them now. >>> >>> Some snapshots are around 1TB already. >>> >>> The last time we tried to delete a ~500GB snapshot the delete task >> blocked the whole diskstore's IO and the whole cluster and all hosts >> became unavailable. >> >> Is there a way to delete large snapshots in a "humane" way that will not >> block everything? >> >> Cheers, >> Stefan >> >> >
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