[libvirt-users] Non-persistent disk

[Eric Blake]

On 08/15/2011 02:01 PM, Xianqing Yu wrote:
> Hi Libvirt team,
>
> I am trying to create a new domain from XML file by using libvirt. I
> want this new domain using non-persistent disk as its disk.
> Non-persistent disk means that when the domain is running, all the
> modification would not be written to disk file. So next time, when you
> boot VM from the same disk file, you would have a fresh disk. I check
> the website but I could not find anything about this. I wonder if
> libvirt support this function.

Yep, I'm working on it, and hope to have it in 0.9.5.  See my RFC here:

https://www.redhat.com/archives/libvir-list/2011-August/msg00552.html

You will basically call out:

<devices>
   <disk ...>
     ...
     <transient/>
   </disk>
  ...

> FYI, if I use KVM, I can use command "qemu-kvm -snapshot" to boot a VM
> on non-persistent disk.

Unfortunately, that makes for a non-migrateable VM - so I'm working on 
something a bit more robust that stands a chance of creating a transient 
yet migrateable domain.

-- 
Eric Blake   eblake at redhat.com    +1-801-349-2682
Libvirt virtualization library http://libvirt.org