On Tue, Nov 23, 2021 at 10:36 PM 151448592 <151448592@xxxxxx> wrote: > > I have a quesion, when we create rbd snap, the snap_seq will add one. If we delete snap,would snap_seq will be reused? or the snap_seq is always monotonic increasing? The snap_seq is a monotonically-increasing value. It's a 'seq'uence number used to indicate that the set of allocated snapshots has changed. > In addition, when we create snap, the monitor will return snap_seq to rbd, the RBD metadata save the snapshot name and snap_seq. Does the monitor need to send the create snap command to OSD? Nope, one the OSD side snapshots are created implicitly when a write operation contains them in the snapset. > When we delete snap, we delete the metedata in RBD and sent delete snap to monitor. Does the monitor send to corresponding OSD to delete snap according the crush method? There's a deleted_snaps set in the OSDMap, and when OSDs process the map that adds them they queue up the snapshot for deletion where it exists within their PGs. (Or maybe it's called deleting_snaps?) Once upon a time that set lived for eternity as an interval set, but these days we track the snaps that have yet to be deleted, and the OSDs report when they've finished deleting so that the set can be trimmed. -Greg _______________________________________________ Dev mailing list -- dev@xxxxxxx To unsubscribe send an email to dev-leave@xxxxxxx
