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(a)widodh.nl&gt; --- src/storage/storage_backend_rbd.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/src/storage/storage_backend_rbd.c b/src/storage/storage_backend_rbd.c index 8c7a80d..3ab7912 100644 --- a/src/storage/storage_backend_rbd.c +++ b/src/storage/storage_backend_rbd.c @@ -283,7 +283,7 @@ static int volStorageBackendRBDRefreshVolInfo(virStorageVolDefPtr vol, int r = 0; rbd_image_t image = NULL; - r = rbd_open(ptr->ioctx, vol->name, &image, NULL); + r = rbd_open_read_only(ptr->ioctx, vol->name, &image, NULL); if (r < 0) { ret = -r; virReportSystemError(-r, _("failed to open the RBD image '%s'"), -- 1.9.1