On Tue, Aug 8, 2017 at 11:42 AM, Aleksei Gutikov <aleksey.gutikov@xxxxxxxxxx> wrote: > Hello > > I've just created a bug about list of watchers of rbd image and list of > clients actually using this rbd image: http://tracker.ceph.com/issues/20943 > > During reproducing of this bug several questions raised: > > 1) Does watcher in rbd status output should be treated as 100% reliable mark > that disk was mapped? No. A watch generally means that the image is "open" in rw mode, but not necessarily by the kernel client. rbd CLI tool opens images in rw mode when performing maintenance operations, you can do it yourself through the API, there are various external daemons, etc. > > 2) And in other way: Does watcher absence should be treated as 100% reliable > mark that disk was not mapped? No. A watch can be temporarily lost and you can catch the client in the process of reestablishing the watch. > > 3) And finally: Is it possible to restrict to map disk on several clients in > the same time (exclusive mapping)? Yes. Use "rbd map -o exclusive" (supported since kernel 4.12). Thanks, Ilya -- To unsubscribe from this list: send the line "unsubscribe ceph-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
