Re: [libvirt] [PATCH] rbd: Open in Read-Only mode when refreshing a volume

On 01/28/2016 05:20 AM, Wido den Hollander wrote:

By opening a RBD volume in Read-Only we do not register a watcher on the header object inside the Ceph cluster.

Refreshing a volume only calls rbd_stat() which is a operation which does not write to a RBD image.

This allows us to use a cephx user which has no write permissions if we would want to use the libvirt storage pool for informational purposes only.

It also saves us a write into the Ceph cluster which should speed up refreshing a RBD pool.

rbd_open_read_only() is available in all librbd versions which also support rbd_open().

Signed-off-by: Wido den Hollander <wido@widodh.nl> --- src/storage/storage_backend_rbd.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)

ACK - and pushed John