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

[Brad Plant <bplant@xxxxxxxxxxxx>]

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@xxxxxxxxxxx> 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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