On 02/13/2011 02:30 PM, Nataraj wrote:
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.
Nataraj
I guess this is not the case. You can attach the VM virtual disk to the loopback and see the VG and it's LV's, but they show up as unavailable. I guess changing the snapshot to be available would be writing to the LV structure and could cause corruption while the vm is running, so better not.
Nataraj