On Wed, Jan 27, 2016 at 11:20:07AM +0100, Wido den Hollander wrote:
> This new algorithm adds support for wiping volumes using TRIM.
>
> It does not overwrite all the data in a volume, but it tells the
> backing storage pool/driver that all bytes in a volume can be
> discarded.
>
> It depends on the backing storage pool how this is handled.
>
> A SCSI backend might send UNMAP commands to remove all data present
> on a LUN.
>
> A Ceph backend might use rbd_discard() to instruct the Ceph cluster
> that all data on that RBD volume can be discarded.
>
> Signed-off-by: Wido den Hollander <wido@xxxxxxxxx>
> ---
> include/libvirt/libvirt-storage.h | 3 +++
> src/storage/storage_backend.c | 4 ++++
> tools/virsh-volume.c | 2 +-
> tools/virsh.pod | 1 +
> 4 files changed, 9 insertions(+), 1 deletion(-)
>
> diff --git a/include/libvirt/libvirt-storage.h b/include/libvirt/libvirt-storage.h
> index 2c55c93..232b4d3 100644
> --- a/include/libvirt/libvirt-storage.h
> +++ b/include/libvirt/libvirt-storage.h
> @@ -153,6 +153,9 @@ typedef enum {
>
> VIR_STORAGE_VOL_WIPE_ALG_RANDOM = 8, /* 1-pass random */
>
> + VIR_STORAGE_VOL_WIPE_ALG_TRIM = 9, /* 1-pass, trim all data on the
> + volume by using TRIM or DISCARD */
> +
Do we need a separate flag for that?
VIR_STORAGE_VOL_WIPE_ALG_ZERO already has a similar behavior
for sparse files, where we truncate the file size to 0,
then back to the original size.
We could treat it as 'rbd_discard' in the rbd driver, with a fallback to
writing zeroes if that's not supported.
Jan
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