[CentOS-virt] KVM virtio block layer - is TRIM/DISCARD supported?

Sat Feb 2 15:58:51 UTC 2013
Nico Kadel-Garcia <nkadel at gmail.com>

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.