libvirt users - Nov 2014 - fstrim support in libvirt/qemu guests

Hi,
I'm trying to find out how to enable fstrim support for libvirt/qemu
guests. Specifically I'm trying to enable this on a CentOS 7 host (qemu
1.5). I searched the web but only found very vague information and no
clear documentation on the requirements or how to modify the guest xml
to enable discard/fstrim support.

Can someone point me in the right direction?

Regards,
  Dennis

On 01.11.2014 05:30, Dennis Jacobfeuerborn wrote:
> Hi,
> I'm trying to find out how to enable fstrim support for libvirt/qemu
> guests. Specifically I'm trying to enable this on a CentOS 7 host (qemu
> 1.5). I searched the web but only found very vague information and no
> clear documentation on the requirements or how to modify the guest xml
> to enable discard/fstrim support.
>
> Can someone point me in the right direction?
One thing that you'll need is the guest agent:

   http://wiki.libvirt.org/page/Qemu_guest_agent

Then you can just use:

   # virsh domfstrim $dom

Michal

On Mon, Nov 3, 2014 at 4:24 PM, Michal Privoznik <mprivozn@redhat.com>
wrote:
> On 01.11.2014 05:30, Dennis Jacobfeuerborn wrote:
>>
>> Hi,
>> I'm trying to find out how to enable fstrim support for
libvirt/qemu
>> guests. Specifically I'm trying to enable this on a CentOS 7 host
(qemu
>> 1.5). I searched the web but only found very vague information and no
>> clear documentation on the requirements or how to modify the guest xml
>> to enable discard/fstrim support.
>>
>> Can someone point me in the right direction?
>
>
> One thing that you'll need is the guest agent:
>
>   http://wiki.libvirt.org/page/Qemu_guest_agent
>
> Then you can just use:
>
>   # virsh domfstrim $dom
>
> Michal
... and probably discard-aware block driver (although I cannot name
anything except virtio-blk which is not supporting trim or will not
support in the near future). Not sure to which part, guest-host
interaction or driver abilities, the initial question belongs.