[Libvir] [RFC]OpenVZ XML def

[Daniel P. Berrange]

On Wed, Mar 14, 2007 at 12:32:36AM +0530, Shuveb Hussain wrote:
> Hi,
> 
> >    - os: that's probably one place where OpenVZ may be quite different 
> >    from
> >      Xen and QEmu, still what does the string 
> >      'slackware-10.2-i386-minimal'
> >      mean ? Is that a pointer to a file ? If yes shouldn't the associated
> >      content be in the XML instead
> 
> Under OpenVZ, there is no choice for the user as far as the OS is
> concerned. He has to live with Linux and Linux alone :-)
> 
> So, in OpenVZ I think there is not need to specify '<os>' at all. When
> we are talking about a template, we are actually talking about what
> becomes the file system for the VM, so we should probably have
> something like this:
> 
>    <disk>
>        <template>fedora-core6-i386-minimal</template>
>    </disk>
> 
> Also, it is possible to specify VM level and VM user/grp level disk
> quotas for VMs in number of  1K blocks. These can also go under the
> 'disk' tag. But I think I will discuss this later.
> 
>    <disk>
>        <template>fedora-core6-i386-minimal</template>
>        <quota level='vm'>102400</quota>
>        <quote level='user' username='root'>102400</quota>
>    </disk>

Looking at the kind of information you need to represent for a guest 
filesystem I think we might be better off inventing a new tag here
instead of using <disk>.  The <disk> tag is really about exposing
some file / device as a virtual disk to the guest OS. OpenVZ doesn't
have any formal concept of virtual disks - it is really a just dealing
in terms of a filesystem. Having the info under <disk> doesn't help
any applications like virt-install / virt-manager because the contents
of the <disk> element bears no resemblance to that used for Xen / QEMU.

So I think this is a really a fundamental modelling difference for VM
based virtualization, vs container based virtualization and thus we
should invent a new tag here.

I've not got a good name yet, so I'll just suggest:

   <filesystem>
      <template>fedora-core6-i386-minimal</template>
      <quota level='vm'>102400</quota>
      <quote level='user' username='root'>102400</quota>
   </filesystem>

Other ideas  instead of 'filesystem' could be 'image', 'root', or 'container'

Dan.
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