[Ovirt-devel] Questions about Xen support

[Pierre Inglebert]

Hi ovirt,

I'm working on the Xen support for oVirt, so first i wanna know if
anyone else is working on or is interrested to.

Thanks to libvirt, it is quite easy to make ovirt only work with Xen or
KVM but not with both because there are some hardcoded parts for KVM.

This hardcoded parts are in task-omatic (especially in task_vm.rb),
libvirt uri connections as "qemu+tcp://" don't work with Xen, so i'm
trying to find a way to dynamicly modify this uri (e.g.change it to "xen
+tcp://" for xen).

To do this, we have to know the hypervisor type before the connection,
we also have to know what type of VM we are creating in case of many
hypervisor types available and for the migration, the hosts need to have
the same hypervisor.

For me, there are 2 solutions.
The first solution is to allow an host to have more than one
hypervisor, these solutions require some changes : 
- the VM will have an hypervisor type
- On the host, a list of available hypervisors (possibly dynamic?)
- For the user, we have to ask about hypervisor/arch on the VM creation
form (from the list of available hypervisors (dynamic listing will be
hard))
- for the VM creation/migration task, we have to check if the Host is
compatible with the VM, 
- during the Host addition, we have to get all the hypervisor
capabilities.

The second solution is to keep the restriction of one hypervisor by
Host.
We can seperate 2 cases :
- One Hypervisor by Host collection :
   - Check the availability of the hypervisor during the Host addition.
   - Move the Hypervisor Type to the Host collection (actually on Host)	

- One Hypervisor by Host (Multiple for Collection) :
   - Ask user about the hypervisor to use during the Host addition
(possibility to choose it from a list)
   - For the VM creation, ask the user about the hypervisor type from
the hypervisor list of the Host Collection.
   - For migration, check available hosts in the Collection.

So I wanna know what do you think about it.

-- 
Pierre Inglebert <Pierre.Inglebert at inria.fr>