[libvirt-users] ubuntu, libvirt and virtio block devices

[Jeff Dickens]

Hi.  Sorry to reply to my own post, but I guess I need to follow up with a
simpler question.

Is anyone here running a VM with libvirt, KVM, a raw LVM disk and has it
set up with type='block' and target bus='virtio' ?


On Tue, Mar 5, 2013 at 12:51 PM, Jeff Dickens <jeff at seamanpaper.com> wrote:

>
>
> --
> Hi. I'm running
> Ubuntu Precise
> 12.04 LTS. I created some virtual machines using vmbuilder, and then
> migrated those from their .qcow files to lvm. However, those virtual
> machines are still using disk type "file":
> Code:
>
>     <disk type='file' device='disk'>
>       <driver name='qemu' type='raw'/>
>       <source file='/dev/vg1/lvname'/>
>       <target dev='hda' bus='ide'/>
>       <alias name='ide0-0-0'/>
>       <address type='drive' controller='0' bus='0' unit='0'/>
>     </disk>
>
> Now I've noticed that this disk should probably have type "block" - using
> this is supposed to provide superior performance. It would also make
> Berteaud's virt-backup script happy and willing to snapshot the lvm making
> the backup very quick. So I tried setting up the disk like this:
>
> Code:
>
> <disk type='block' device='disk'>
>       <driver name='qemu' type='raw'/>
>       <source dev='/dev/vg1/lvname'/>
>       <target dev='vda' bus='virtio'/>
>       <address type='pci' domain='0x0000' bus='0x00' slot='0x05' function='0x0'/>
>     </disk>
>
> I had to edit fstab to look for the disk on vda instead of hda but it came
> up. However performance was terrible. It seemed like it was going to lock
> up, although it never did.
>
> So my question
> is:
>
> *How should I be setting up my LVM-based virtual machines to use virtio
> block devices ?*
>
>
>      IT Manager      978-632-1513
>
>


-- 
*     Jeff Dickens*
     IT Manager      978-632-1513
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