[ovirt-users] How do I get discard working?

[Chris Adams]

Once upon a time, Fabian Deutsch <fdeutsch at redhat.com> said:
> I'm not sure which qemu disk drivers/busses support this, but at least virtio does so.
> I'm using it for development.

Using CentOS 7, I think qemu-kvm only supports discard on virtio-scsi
drives using the raw format.  Discard on qcow2 images is supported for
newer versions of qemu-kvm.

oVirt uses virtio by default; you can switch to virtio-scsi.  However,
if you use thin-provisioned disks, oVirt uses qcow2 format, so discard
is not supported with CentOS 7's version of qemu-kvm.

-- 
Chris Adams <cma at cmadams.net>