[libvirt-users] libvirt live migrate problem

[Paul Boven]

Hi,

On 04/02/2014 12:34 PM, lyz_pro wrote:
> The problem is after I successful live migrate a domain, the domain
> os  become read-only.
> and when I use qemu-img to show the disk info at node which domain
 > current running ,
> the command return 'Permission denied'. BUT, I can use qemu-img show
> the disk info at the previous node.

If you are using glusterfs, libvirt doesn't recognize it as a 'shared'
filesystem, and therefore does a 'chown' back to root:root when stopping
the image on one host, which gets into a race with chowning to
lilbvirt:qemu on the other. If the image ends up being owned by 
root:root, then the guest no longer has access to the file system, and 
switches to read-only.

There is a bug for this:

https://bugzilla.redhat.com/show_bug.cgi?id=1057645

The workaround is: to change /etc/libvirt/qemu.conf so it contains
"dynamic_ownership=0", and restart libvirt.

In comment 7 of the bug I described doing it by bringing all the guests
down, but I think you might be able to get away with just changing the
config file and restarting libvirt.

Regards, Paul Boven.
-- 
Paul Boven <boven at jive.nl> +31 (0)521-596547
Unix/Linux/Networking specialist
Joint Institute for VLBI in Europe - www.jive.nl
VLBI - It's a fringe science