CentOS virt - Feb 2013 - KVM virtio block layer - is TRIM/DISCARD supported?

Hi,

One question please:

If I use SSD as a storage on a host machine, does KVM's virtio I/O layer
pass the TRIM/DISCARD commands to the SSD?

I guess the question would be twofold:
1) is TRIM supported/forwarded if only one LVM'ed partition of SSD is
forwarded?
2) is TRIM supported/forwarded if full SSD is forwarded (i.e. /dev/sdX)

-- 
Best regards,
        Dmitry Mikhailov

On Sat, Feb 2, 2013 at 5:12 AM, Dmitry E. Mikhailov
<d.mikhailov at infocommunications.ru> wrote:
> Hi,
>
> One question please:
>
> If I use SSD as a storage on a host machine, does KVM's virtio I/O
layer
> pass the TRIM/DISCARD commands to the SSD?
Doesn't look like it, *yet*. That looks like it came out in the 2.6.33
kernels, the upstream vendor for CentOS has only gotten up to 2.6.32.
I wouldn't necessarily call it stable for production use until it's
been out for a while.
>
> I guess the question would be twofold:
> 1) is TRIM supported/forwarded if only one LVM'ed partition of SSD is
> forwarded?
> 2) is TRIM supported/forwarded if full SSD is forwarded (i.e. /dev/sdX)
See above.