[one-users] [OpenNebula 3.6] Problem with persistent images using FileSystem DM & qcow2 TM

[Jaime Melis]

Hello Anton,

I would do something like: http://pastie.org/4695814 (untested!!)

cheers,
Jaime

On Mon, Sep 10, 2012 at 3:33 PM, Anton Gulenko <
anton.gulenko at student.hpi.uni-potsdam.de> wrote:

> Dear Jaime,
>
> thank you for the quick reply.
>
> Thanks to your explanations, we have managed to get the whole process
> working as we wanted it to, without modifying the qcow2-scripts.
>
> But to achieve that, we had to manually convert our image to the
> qcow2-format before importing it into OpenNebula.
> Is there a way to get OpenNebula to do that conversion task
> automatically? E.g. it could detect, when a raw image is imported into
> a
> qcow2-datastore, and instead of simply copying the image, invoke the
> "qemu-img convert" command.
>
> Cheers,
> Anton
>
>
> 2012/9/10 Jaime Melis <jmelis at opennebula.org>:
> > Hello Anton,
> >
> > The qcow2 drivers assume, like with shared, that the datastore is
> exported
> > to the host using a distrubuted file system like NFS.
> >
> > Considering we're talking about persistent images, why bother doing
> > "qemu-img create" and then "qemu-img commit" to save the changes, if you
> can
> > just do "ln -s" and use the image in place? It will be deployed faster,
> > saved faster and more importantly, it will run faster since it won't
> have a
> > backing-store.
> >
> > Since the datastore is exported to the host, the MVDS script is doing
> > "qemu-img convert" only when the image has been marked as SAVE_AS,
> otherwise
> > it silently exits. For the SAVE_AS case, we want a new, indepedent
> image, so
> > we need to use "qemu-img convert".
> >
> > Another thing we wanted to avoid was to have images depending on other
> > images. Consider the case where image A is the backing-store of image B.
> If
> > you remove image A, image B will stop working.
> >
> > cheers,
> > Jaime
> >
> > On Sun, Sep 9, 2012 at 10:13 PM, Anton Gulenko
> > <anton.gulenko at student.hpi.uni-potsdam.de> wrote:
> >>
> >> Dear OpenNebula community,
> >>
> >> We are using OpenNebula 3.6 to set up a private cloud for a university
> >> research project.
> >> We use the FileSystem Datastore Manager and the qcow2 Transfer Manager.
> >> For the preparation of VMs, it is important for us to use persistent
> >> images.
> >> Using non-persistent images posed no problems at all. However,
> >> persistent deploying a VM with a persistent image would not work.
> >>
> >> Inspecting the scripts in the $ONE_LOCATION/var/remotes/tm/qcow2
> >> directory, we noticed, that persistent images are handled the same way
> >> as by the Shared Transfer Manager: by creating a filesystem-link from
> >> the image-datastore into the System-datastore.
> >> Is that really the intention of the ln-script in the qcow2 Transfer
> >> Manager? We had expected a 'qemu-img create' command.
> >> We also noticed, that the mvds-script, that is responsible for
> >> committing the changes of the VM-disk back into the datastore, is
> >> using the 'qemu-img convert' command.
> >> We expected it to use the 'qemu-img commit' command, so that the
> >> changes are pushed back into the backing image-file.
> >>
> >> Did we misunderstand the purpose of the mentioned scripts?
> >>
> >> By making the following changes to the scripts, we got the qcow2
> >> Transfer Manager running just the way we expected it to:
> >> - Delete the original ln-script and replace it with a copy of the
> >> clone-script
> >> - Replace the 'qemu-img convert' command in the mvds-script with an
> >> appropriate 'qemu-img commit' command
> >>
> >> Best regards,
> >> Anton and Frank
> >> _______________________________________________
> >> Users mailing list
> >> Users at lists.opennebula.org
> >> http://lists.opennebula.org/listinfo.cgi/users-opennebula.org
> >
> >
> >
> >
> > --
> > Jaime Melis
> > Project Engineer
> > OpenNebula - The Open Source Toolkit for Cloud Computing
> > www.OpenNebula.org | jmelis at opennebula.org
>



-- 
Jaime Melis
Project Engineer
OpenNebula - The Open Source Toolkit for Cloud Computing
www.OpenNebula.org | jmelis at opennebula.org
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.opennebula.org/pipermail/users-opennebula.org/attachments/20120910/930f7653/attachment-0002.htm>