[libvirt] virsh migrate with libvirt-0.5.1: failed to start listening VM

[Garry Dolley]

On Tue, Jul 14, 2009 at 01:13:03PM -0500, Charles Duffy wrote:
> Scott Baker wrote:
>> You're supposed to have /var/lib/libvirt/images mounted via shared storage 
>> (nfs/cifs/etc) on both machines.
>
> I've heard of folks having trouble doing live migration over NFS -- 
> something with stronger concurrency guarantees (GFS, a shared iSCSI or FC 
> mount [possibly with cLVM to partition it up], etc) is likely to be a safer 
> bet.
>
> (Indeed, looking at the documented preferred environment for VMware's 
> VMotion is probably a good guideline for anything that's going to be 
> trusted with real production usage -- a separate bonded pair of NICs on 
> each host, connected to a dedicated network for communication with the SAN 
> hosting the backing store).

A method I'm going to be trying out very shortly is using DRBD in
dual-primary mode.  DRBD will keep LVM volumes (block devices) for
each VM in sync between two nodes.  Upon migration, writes will
cease on node A and when ready, begin on node B.  You won't have
concurrent writes, so it will be safe to use DRBD directly without a
clustering FS on top (GFS, OCFS2, etc...).  

DRBD has scripts for Xen that take care of the details for you.
Haven't seen the same for KVM/QEMU yet, but I imagine it would be
pretty similar.

-- 
Garry Dolley
ARP Networks, Inc. | http://www.arpnetworks.com | (818) 206-0181
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