[one-users] Beginner questions: Opennebula 2.2.1

[Tino Vazquez]

Hi,

It is not atomic, and in fact is asynchronous. There are various save
and save_as choices (take a look in the documentation). If you are
using NFS with a persistant image, you can bump into this sort of
situations, so special care must be taken with this kind of VMs.

Regards,

-Tino

--
Constantino Vázquez Blanco | dsa-research.org/tinova
Virtualization Technology Engineer / Researcher
OpenNebula Toolkit | opennebula.org



On Fri, May 6, 2011 at 12:50 PM, Steffen Neumann <sneumann at ipb-halle.de> wrote:
> Hi,
>
> one add-on question:
>
> On Fri, 2011-05-06 at 12:15 +0200, Tino Vazquez wrote:
> ...
>> Shutdown represents a more clean approach, the VM is cleanly
>> shut down, and the image saved if marked so.
>
> Is that atomic ? Or under file locking control ?
>
> If I have some place, say /srv/could/goldenimage/ubuntu.img
> where my disk image file is stored, does shutdown then overwrite
> the existing ubuntu.img, and what happens if during the XX seconds
> of writing back a new VM is created from ubuntu.img ?
> Unless "save" is atomic, the new VM will fail on a half-written
> mix of old and new. Or did I miss anything ?
> What happens if three VMs created off ubuntu.img shutdown
> simultanously ? Will each write its changes back
> into that single ubuntu.img ?
>
> Yours,
> Steffen
>
> --
> IPB Halle                    AG Massenspektrometrie & Bioinformatik
> Dr. Steffen Neumann          http://www.IPB-Halle.DE
> Weinberg 3                   http://msbi.bic-gh.de
> 06120 Halle                  Tel. +49 (0) 345 5582 - 1470
>                                  +49 (0) 345 5582 - 0
> sneumann(at)IPB-Halle.DE     Fax. +49 (0) 345 5582 - 1409
>
>
>