Re: [Xen-users] Reverse migration breaks/freezes VM

Thomas Halinka
Fri, 06 Mar 2009 08:34:30 -0000

Hi Florian,

Full ACK to Brad,

kick the 2.6.27-Kernel. We have some kernel-gurus in here and they will
tell you the same. Try 2.6.26 or 2.6.28 and it should work....

Best regards,

Thomas


Am Freitag, den 06.03.2009, 11:09 +1100 schrieb Brad
Plant:
> Hi Florian,
>
> I was unable to successfully migrate VMs running a 2.6.27 kernel. I found
that the network would stop working on the first migration and then the disk IO
would stop when migrating the machine back again (which made processes block
waiting for disk IO and therefore the machine appear to hang).
>
> Try a 2.6.28 kernel. It seems to have sorted out my issues.
>
> Cheers,
>
> Brad
>
>
> On Thu, 5 Mar 2009 14:12:56 +0100
> "Rustedt, Florian" <Florian.Rustedt@smartnet.de> wrote:
>
> > Hello list,
> >
> > I''ve got strange phenomenons with migrations. I think
it''s a bug, but am not sure, so i am asking for your help to find this
ou, please ;)
> >
> > First the construct:
> > Two HP DL180G5(xen0,xen1) with dual-quadcore each, 8G RAM.
> >
> > On each a dom0 with selfcompiled(because of network drivers)
gentoo-sources-xen-2.6.27_amd64 and Xen 3.3.0. The installation is completely
the same (rsynct), only different in ip and hostname.
> >
> > Both share a drbd0(v8.3.0) device. On it an lvm with one lv per vm.
> >
> > Now what''s the problem:
> >
> > If i migrate a running vm(mx1-smartnet-de) from xen0 to xen1, it seems
to work.
> > I could do a "xm migrate mx1-smartnet-de xen1" without any
interuption while having a ssh-connection to the vm and downloading a
kernel-source in it.
> >
> > Then i did a "xm migrate mx1-smartnet-de xen0" on xen1 to
move it back again. After that, the vm freezes at 100%CPU and that''s
it! Can''t connect to it any more, whether via ssh nor via vnc/fb or
console. Only "xm destroy" could help, "xm shutdown" has no
impact.
> >
> > For debugging, i added the concerning parts of the xend.log from each
and the kernel-configs, so that you could try to help me find the prob perhaps
in the logs?
> >
> > Just after having started the vm:
> > xen0_after_start_of_vm.log
> >
> > Then after the first migration:
> > xen0_after_migrate_to_xen1_of_vm.log
> > xen1_after_migrate_to_xen1_of_vm.log
> >
> > And last, after the reverse:
> > xen0_after_migrate_back_from_xen1_of_vm.log
> > xen1_after_migrate_back_from_xen1_of_vm.log
> >
> > I don''t believe it is a drbd/lvm problem, because drbd keeps
in "0: cs:Connected ro:Primary/Primary ds:UpToDate/UpToDate C r---"
and there are no lv-concerning log-entries in syslog.
> >
> > There are of course errors concerning "retry suspend domain
failed", but there''s no hint, WHY this has got failed?
> >
> > Kind regards, Florian
> >
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