[libvirt-users] 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.
On 11/3/2014 8:43 AM, Andrey Korolyov wrote:
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.
The virtio-scsi driver supports it, though you take a minor performance hit for switching.
On 03.11.2014 15:04, Brian Rak wrote:
On 11/3/2014 8:43 AM, Andrey Korolyov wrote:
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.
The virtio-scsi driver supports it, though you take a minor performance hit for switching.
Yes, after a bit of experimentation it seems you need to use virtio-scsi and raw images to make this work. Interesting enough then you can even make use of fstrim in a non-SSD context and shrink the used space of the raw image. Regards, Dennis
participants (4)
-
Andrey Korolyov -
Brian Rak -
Dennis Jacobfeuerborn -
Michal Privoznik