[openstack-dev] [cinder][nova] Proper behavior for os-force_detach
waboring at hemna.com
Wed Jul 18 15:56:07 UTC 2018
The whole purpose of this test is to simulate the case where Nova doesn't
know where the vm is anymore,
or may simply not exist, but we need to clean up the cinder side of
things. That being said, with the new
attach API, the connector is being saved in the cinder database for each
On Wed, Jul 18, 2018 at 5:02 AM, Gorka Eguileor <geguileo at redhat.com> wrote:
> On 17/07, Sean McGinnis wrote:
> > On Tue, Jul 17, 2018 at 04:06:29PM -0300, Erlon Cruz wrote:
> > > Hi Cinder and Nova folks,
> > >
> > > Working on some tests for our drivers, I stumbled upon this tempest
> > > 'force_detach_volume'
> > > that is calling Cinder API passing a 'None' connector. At the time
> this was
> > > added several CIs
> > > went down, and people started discussing whether this
> (accepting/sending a
> > > None connector)
> > > would be the proper behavior for what is expected to a driver to
> do. So,
> > > some of CIs started
> > > just skipping that test and others implemented fixes that
> made the
> > > driver to disconnected
> > > the volume from all hosts if a None connector was received.
> > Right, it was determined the correct behavior for this was to disconnect
> > volume from all hosts. The CIs that are skipping this test should stop
> doing so
> > (once their drivers are fixed of course).
> > >
> > > While implementing this fix seems to be straightforward, I feel that
> > > removing the volume
> > > from all hosts is not the correct thing to do mainly considering that
> > > can have multi-attach.
> > >
> > I don't think multiattach makes a difference here. Someone is forcibly
> > detaching the volume and not specifying an individual connection. So
> based on
> > that, Cinder should be removing any connections, whether that is to one
> > several hosts.
> I agree with Sean, drivers should remove all connections for the volume.
> Even without multiattach there are cases where you'll have multiple
> connections for the same volume, like in a Live Migration.
> It's also very useful when Nova and Cinder get out of sync and your
> volume has leftover connections. In this case if you try to delete the
> volume you get a "volume in use" error from some drivers.
> > > So, my questions are: What is the best way to fix this problem? Should
> > > Cinder API continue to
> > > accept detachments with None connectors? If, so, what would be the
> > > on other Nova
> > > attachments for the same volume? Is there any side effect if the
> volume is
> > > not multi-attached?
> > >
> > > Additionally to this thread here, I should bring this topic to
> > > Cinder's meeting,
> > > so please join if you have something to share.
> > >
> > +1 - good plan.
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