Re: How to do an automated backup?

[Avi Kivity <avi@redhat.com>]

Steve Lorimer wrote:
> Ok, should be a simple question here:  How to backup a KVM host image.
>
> My first plan - failure:
> 1) Suspend / hibernate (using virsh ... save) image to disk
> 2) Backup vm disk image & suspend file
> 3) Backup .xml
> 4) Restore suspended image
> This would accomplish a backup that could be reactivated very quickly 
> as bootup would not even be required.
> However, in testing it failed.  Of two VM's tried, one worked, but the 
> other one never came back up.  The network interface never reenabled 
> and this system itself sat maxing out it's cpu core until manually 
> terminated.
>

That's a bug.  If you can reproduce this on the latest kvm, and provide 
instructions for us on how to reproduce this, we will try to fix it.

> My second plan:
> 1) Use virsh to shutdown the VM
> 2) Backup vm file & xml
> 3) Start vm (regular bootup)
> This takes longer, but can be tolerated in order to get a backup.  
> However, this fails also:
> virsh -c qemu:///system shutdown kvmtest
> The command fails to send any kind of shutdown request to the VM 
> guest.  As a result, the only thing that works is to kill it (the 
> virsh command for that does work).  However, this is not acceptable 
> for a backup.
>
> Nothing out of the ordinary in my system setup:
> VM Server:  Ubuntu Server
> Guest OS's: Also Ubuntu
>
> Any thoughts, advice?

If your backing store supports snapshots (btrfs, lvm) you could create a 
snapshot while the guest is running, and backup the snapshot.

The integrity of the backup depends on whether the guest is able to 
recover from restarts.

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