Re: [Xen-users] cloning guests between Dom0's ?

[John Haxby <john.haxby@xxxxxxxxxx>]

Simon Hobson wrote:
> Ferreira, N.L. wrote:
>
> > For a LVM LV you can do the following (using the LVM snapshot) 
> > without shutting down the domU:
> > lvcreate -s /dev/vg/domU -L1G -n domU_snap
> > mkdir /mnt/domU_snap
> > mount /dev/vg/domU_snap /mnt/domU_snap
> > tar cvjpf /storage/path/domU_snapshot.tbz /mnt/domU_snap
> > lvremove /dev/vg/domU_snap
> Is this correct ? I know the LVM snapshot will give you a "point in 
> time" image, but won't the DomU have unwritten changes in it's cache - 
> giving you a very unclean filesystem ?
You probably want to use kpartx on the snapshot and mount the right 
partition for backups.   However, as you'll say, you'll probably come 
unstuck when you try to mount the file system because it will be 
corrupt.  You need to cooperation of both the OS and any running 
applications in the domU for this approach to work.  A good way to get 
everything consistent for backing up is to shut down the guest OS, take 
the snapshot and the re-start the guest OS.   Or at least have the guest 
unmount the file system(s) you're going to back up before you take the 
snapshot.
Backing up data from a machine (physical or virtual) is surprisingly 
difficult unless you can enlist the help of the machine.   It's almost 
always easier to do it from within the machine.
jch

_______________________________________________
Xen-users mailing list
Xen-users@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-users