Change in vdsm[master]: vm: enable disk stats collection on recovery

fromani at redhat.com fromani at redhat.com
Fri Sep 5 07:49:01 UTC 2014


Francesco Romani has posted comments on this change.

Change subject: vm: enable disk stats collection on recovery
......................................................................


Patch Set 1: Code-Review-1

This issue turned out to be much less severe than I thought.

What saves us is that as last step of recovery flow, in

clientIF.py:_recoverExistingVms()

there is a specific preparePaths() invocation for each recovered VM,
which will clean things and starts the collection of the disk stats

Why I was confused and thus proposed this change?
I was doing stress-test on VDSM with 100Vms with unrealistically
frequent polling (each 1s)
looking for memleaks, and, as side effect of the above, disk stats
for *each* VMs aren't reported until recovery is fully completed.

I didn't saw disk stats just after recovery, and during the initial investigation
I took the wrong turn and git grep'd for the wrong statement (didn't
check properly preparePath, only inside vm.py), hence my error.

I apologize for that, I'll make a point to always have a clear and simple
reproducer, ready for BZ, before to cry wolf.

That said, there is still an issue with disk stats and disk extend
being ineffective during *all the recovery phase*, and for code
in recovery path being confusing and twisted, but this is much
less serious than the issue originally reported.

I think is safe to abandon this change, take notes for possible
improvements on the recovery flow, and to move on.

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Gerrit-MessageType: comment
Gerrit-Change-Id: Ibd7d32373f5a0a7dd4ef88c5a0ad5a9f3d52938c
Gerrit-PatchSet: 1
Gerrit-Project: vdsm
Gerrit-Branch: master
Gerrit-Owner: Francesco Romani <fromani at redhat.com>
Gerrit-Reviewer: Dan Kenigsberg <danken at redhat.com>
Gerrit-Reviewer: Francesco Romani <fromani at redhat.com>
Gerrit-Reviewer: Michal Skrivanek <michal.skrivanek at redhat.com>
Gerrit-Reviewer: Nir Soffer <nsoffer at redhat.com>
Gerrit-Reviewer: Vinzenz Feenstra <vfeenstr at redhat.com>
Gerrit-Reviewer: automation at ovirt.org
Gerrit-Reviewer: oVirt Jenkins CI Server
Gerrit-HasComments: No


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