[Xen-users] Reverse migration breaks/freezes VM

Rustedt, Florian
Thu, 05 Mar 2009 13:12:56 -0000

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