Von: Stefan Wendler [stefan.wendler@tngtech.com]=0A= Gesendet: Montag, 27. Oktober 2014 11:39=0A= An: Markus Stockhausen=0A= Cc: users@ovirt.org=0A= Betreff: Re: [ovirt-users] Deleting large snapshots blocks the whole clus= ter=0A= =0A= Hi,=0A= =0A= do you mean during snapshot deletion or in general?=0A= =0A= In general we do not have any swap usage at all. On none of the 4 hosts.= =0A= =0A= We had some swap I/O on the host that is SPM most of the time. But not=0A= during that period where we tried to delete the snapshot.=0A= =0A= =0A= I thought of the bug described in RH bugzilla 1138690 "[SCALE] snapshot del= etion -> =0A= heavy swapping on SPM". In case you have no access to it (as it is RHEV tag= ged): =0A= =0A= qemu-img reads through pagecache during snapshot deletion. A new flag has b= een =0A= intrduced in August this year that allows to avoid page cache. This flag mu= st be=0A=
This is a multi-part message in MIME format. ------=_NextPartTM-000-a0780f88-f591-414a-acb9-ba0b16afdc8d Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable provided by OVirt/RHEV. Target release is 3.6. =0A= =0A= Until then the only bugfix is to drop pagecache manually on regular interva= ls on the =0A= hypversior and especially the SPM node.=0A= =0A= Markus=0A= =0A=
=0A= Cheers,=0A= Stefan=0A= =0A= On 10/27/14 11:08, Markus Stockhausen wrote:=0A=
Do you see swapping on the SPM? If yes a regular echo 3 > drop_caches c= ould help.=0A= =0A= Markus=0A= =0A= Am 27.10.2014 10:57 schrieb Stefan Wendler <stefan.wendler@tngtech.com>= :=0A= Hi,=0A= =0A= we have some really large snapshots left from a migration. Since our=0A= store is almost full now we have to delete them now.=0A= =0A= Some snapshots are around 1TB already.=0A= =0A= The last time we tried to delete a ~500GB snapshot the delete task=0A= blocked the whole diskstore's IO and the whole cluster and all hosts=0A= became unavailable.=0A= =0A= Is there a way to delete large snapshots in a "humane" way that will not= =0A= block everything?=0A= =0A= Cheers,=0A= Stefan=0A= =0A= =0A= =0A= ------=_NextPartTM-000-a0780f88-f591-414a-acb9-ba0b16afdc8d Content-Type: text/plain; name="InterScan_Disclaimer.txt" Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename="InterScan_Disclaimer.txt"
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