libvirt users - Mar 2013 - ubuntu, libvirt and virtio block devices

-- 

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

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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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