This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --pRrw2Nflj1DiHOHuNiU2AGGrNfrnE9WXR Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: quoted-printable 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.wendler@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 c= luster
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 host= s.
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.
=20 I thought of the bug described in RH bugzilla 1138690 "[SCALE] snapshot= deletion ->=20 heavy swapping on SPM". In case you have no access to it (as it is RHEV= tagged):=20 =20 qemu-img reads through pagecache during snapshot deletion. A new flag h= as been=20 intrduced in August this year that allows to avoid page cache. This fla= g must be provided by OVirt/RHEV. Target release is 3.6.=20 =20 Until then the only bugfix is to drop pagecache manually on regular int= ervals on the=20 hypversior and especially the SPM node. =20 Markus =20
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.wendler@tngtech.co=
m>:
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 n= ot block everything?
Cheers, Stefan
=20
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