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From Ahmad Emneina <aemne...@gmail.com>
Subject Re: [RFC]Bypass Libvirt storage pool for NFS
Date Wed, 19 Mar 2014 21:04:10 GMT
I'm all for adding a bit of additional smarts to cloudstack so it can
workaround the current KVM limitations. Waiting for anything to get fixed
up stream is affecting deployments NOW, and a bit utopian. cloudstack seems
to be the lower barrier to entry on getting these scenarios addressed.


On Wed, Mar 19, 2014 at 1:29 PM, Edison Su <Edison.su@citrix.com> wrote:

> It's hard to find root cause and fix something in libvirt, even we found
> the root cause, it's hard to push the fix into libvirt upstream, and not to
> say push into downstream, like RHEL 6 etc. For example, we already have a
> fix for the bug https://bugzilla.redhat.com/show_bug.cgi?id=977706 for a
> few month now, there is no resolution to resolve the issue. Without the
> fix, we just simply are blocked to support newer version of KVM.
>
> So if community doesn't like what I proposed, then how about another way:
> I will write a new implementation of KVMStoragePool interface, which will
> be backed by java/python/shell script, it won't be enabled by default.
>  It's a simple thing, don't understand why libvirt gets it done so
> complicated, and introduce a lot of pain.
>
> > -----Original Message-----
> > From: Nux! [mailto:nux@li.nux.ro]
> > Sent: Wednesday, March 19, 2014 12:35 PM
> > To: dev@cloudstack.apache.org
> > Subject: Re: [RFC]Bypass Libvirt storage pool for NFS
> >
> > On 19.03.2014 19:01, Wido den Hollander wrote:
> > > On 03/19/2014 07:54 PM, Edison Su wrote:
> > >> I found many times in QA's testing environment, the libvirt storage
> > >> pool(created on NFS) is missing on the kvm host frequently, for no
> > >> reason. It may relate to bug
> > >> https://bugzilla.redhat.com/show_bug.cgi?id=977706.
> > >> In order to fix this issue, and bug CLOUDSTACK-2729, we added a lot
> > >> of workaround to fight with libvirt, such as, if can't find the
> > >> storage pool, then create the same pool again etc. As the storage
> > >> pool can be lost on kvm host at any time, it will cause a lot of
> > >> operation errors, such as can't start vm, can't delete volume etc,
> etc.
> > >> I want to bypass libvirt storage pool for NFS, as java itself,
> > >> already have all the capabilities that libvirt can provide, such as
> > >> create a file, delete a file, list a directory etc, there is no need
> > >> to add another layer of crap here. In doing so, we won't be blocked
> > >> by libvirt bug(https://bugzilla.redhat.com/show_bug.cgi?id=977706) to
> > >> support newer version of KVM.
> > >>
> > >
> > > -1
> > >
> > > I understand the issues which we see here, but imho the way forward is
> > > to fix this in libvirt instead of simply go around it.
> > >
> > > We should not try to re-invent the wheel here, but fix the root-cause.
> > >
> > > Yes, Java can do a lot, but I think libvirt can do this better.
> > >
> > > For the RBD code I also had a couple of changes go into libvirt
> > > recently and this NFS issue can also be fixed.
> > >
> > > Loosing NFS pools in libvirt is most of the times due to a restart of
> > > libvirt, they don't magically disappear from libvirt.
> > >
> > > I agree that we should be able to start the pool again even while it's
> > > mounted, but that's something we should fix in libvirt.
> > >
> > > Wido
> >
> > -1 and 100% with Wido. If libvirt gets fixed then it would save loads of
> code in
> > the future and bring other benefits (think support for Xen Project via
> libvirt
> > etc).
> > Let's push for libvirt fix instead.
> >
> > My 2 cents,
> > Lucian
> >
> >
> > --
> > Sent from the Delta quadrant using Borg technology!
> >
> > Nux!
> > www.nux.ro
>

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