[Users] oVirt support for backup/restore

[Itamar Heim]

On 04/03/2013 14:57, Ricky Schneberger wrote:
> On 2013-03-04 13:24, Jiri Belka wrote:
>> On Mon, 04 Mar 2013 12:52:53 +0100 Ricky Schneberger
>> <ricky at schneberger.se> wrote:
>>
>>>> Live snapshot does not save memory state, IIRC. So either
>>>> shutdown all VMs or do not think about this as solid backup
>>>> solution.
>>>>
>>>
>>> Hi, If I dont think about it as a solid solution, is it doable?
>>> Even with a manual live snapshot I will lack this memory state,
>>> right?
>>>
>>> All I want if I must restore a snapshot is to get the WM up on
>>> track in an earlier state.
>>
>> The "snapshot" like in VMWare world which saves even memory is
>> called checkpoint in qemu-kvm world. And IIRC it is not implemented
>> yet.
>>
>> Live snapshot is doable, no problem. The problem can be your
>> design. As you know a lot of apps do not write to filesystem
>> immediately, so snapshot backup is useless. So either
>> shutdown/think twice or forget it.
>>
>> But others can have different view... Backup is thing you _must_
>> trust, if you design is broken, the consequences are terrific! If
>> your goal is to have fast disaster recovery, then why not to have
>> backup machine or some clustered solution?
>>
>> jbelka
>>
>
> Thanks for your answer.
>
> We have both Netvault and Acronis on the most of the VMs, but then we
> have other VMs in the cluster that we want a daily scheduled snapshot
> implementation on, but we dont want to setup a complete backup
> solution on this VMs. It's testmachines, different virtual desktops,
> OCR-readers and so on. We have no needs of snapshots like in VMWare
> world for them, nor even a complete backup solution. There I think
> Ovirts snapshot handling should be perfect.
>

in general, you are correct - you don't care about live snapshot with 
memory, since you probably mostly care about backing up the disks.
you may care, depending on the type of guest, on having a 
qemu-guest-agent installed, which would help with syncing the writes to 
the disks before the live snapshot is taken.

something to test though is if a daily snapshot does not degrade the 
performance of the running VM, due to more COW layers (until the backup 
api and live merge are in place).