[virt-tools-list] Best way to backup my VMs

Frédéric Grelot fredericg_99 at yahoo.fr
Tue Apr 12 15:50:37 UTC 2011

> Actually, this isn't right.  Think about the case where you lose
> power to
> your computer; you don't get corrupted disks, you get
> "crash-consistent" disks
> (this is what journaling filesystems are for).  So if you know what
> you are
> doing, it is sufficient just to pause the guest (virsh suspend
> <guest>), take
> the backup, and then resume the guest (virsh resume <guest>).  True,
> you
> won't get all of the data that might have been in-flight in memory,
> but it
> should be a valid state of the disk.

I tend to agree with that, it already happened to me for a zimbra server, and I lost nothing.

> That all being said, installing backup software in the guest is the
> best
> course of action.

An other method to profit from virtualization-enabled server would be to take the following actions :
-inside guest : turn of server application
-inside guest : unmount data disk
-host : pause guest (necessary?)
-host : lvm (or qcow/qed) snapshot of disk
-host : resume guest
-inside guest : remount and restart server application

Provided there is no side-effect of unmounting with regard to guest cache (to be confirmed), I think this would reduce downtime, and permits backup of specific parts of the server application without stopping it as a whole.
A (maybe safest) other option would be to gracefully shutdown the server, LVM/qcow/qed snapshot its disk and restart the server immediately : the data duplication itself won't account for the downtime, since it can be done later.


> --
> Chris Lalancette
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