[CentOS-virt] using an lvm for kvm vm

Sun Feb 13 22:30:54 UTC 2011
Nataraj <incoming-centos at rjl.com>

On 02/13/2011 10:21 AM, Dennis Jacobfeuerborn wrote:
>> Could you then pause the virtual machine and safely take an LVM
>> snapshot, continue the VM and then mount the snapshot on the host and do
>> a backup?
> Probably not. If you pause the guest then the filesystem on it might be in 
> an inconsistent state. You will be able to make a snapshot since that 
> happens on the block level but you might have problems mounting it.
> Regards,
>    Dennis
I've heard of somebody doing something to make this work. I think you
could create another LV (from inside the VM - assuming a linux VM) on
top of whatever raw partition was available to the VM.  Then you could
take the snapshot within the VM (which I believe guarantees that the
filesystem is sync'ed when the snapshot is taken.)  Then you use losetup
and lvscan to make the lvm vg available on the host and I think you
could access the snapshot without even pausing the vm.