I think I might be confused. When creating a group snapshot, we have the ConsistencyGroupSnapshot that allows you to store the necessary linkage between the image's snapshot and its associated group snapshot [1]. Why not just name the image's snapshots to the same name as the parent group snapshot name and search the snapshot's metadata to get the linkage? [1] https://github.com/ceph/ceph/blob/master/src/cls/rbd/cls_rbd_types.h#L255 On Tue, Dec 13, 2016 at 8:03 PM, Victor Denisov <vdenisov@xxxxxxxxxxxx> wrote: > Jason, > > My current implementation of consistency group snapshot feature names > image snapshots like: <group_pool>_<group_id>_<group_snap_id> > I rely on this fact when I need to remove a consistency group. It's > necessary because if some of image snapshots were created, but the > whole group snapshot operation failed, > then the only way to find those dangling image snapshots is by this name. > > It means that we should forbid renaming snapshots from > ConsistencyGroupSnapshot namespace. > > Another option is to allocate image snapshot ids during the creation > of group snapshot, but this requires a major rewrite of the whole > process of snapshot creation for images. > > What is your opinion on this? > > Thanks, > V. > > > On Tue, Nov 1, 2016 at 8:01 AM, Jason Dillaman <jdillama@xxxxxxxxxx> wrote: >> I chatted with Xing on IRC this morning re: Cinder generic groups. It >> sounds like RBD will need to support preserving the image's >> consistency group snapshots even if the image is removed from the >> group. In the OpenStack case, you won't have to worry about the image >> being deleted while it still has associated group snapshots. >> >> We will also want to support being able to clone child images from a >> group snapshot to ensure that we can thin provision new groups volumes >> when creating a new group from a group snapshot. This means that the >> group snapshots should be able to be protected/unprotected just like >> standard user snapshots. >> >> On Mon, Oct 31, 2016 at 9:07 AM, Jason Dillaman <jdillama@xxxxxxxxxx> wrote: >>> Looking at the Cinder codebase, I don't see any such restriction that >>> would prevent you from removing a volume from a consistency group that >>> has associated snapshots. I would double-check on the OpenStack >>> development mailing list if this is correct and is the intent. Worst >>> case, the RBD driver could raise an exception if there are still >>> consistency group snapshots associated to the image. >>> >>> >>> On Fri, Oct 28, 2016 at 6:41 PM, Victor Denisov <vdenisov@xxxxxxxxxxxx> wrote: >>>> Another thing that bothers me. When we remove an image from a consistency group. >>>> Should we remove all snapshots of this image that were created as part >>>> of a consistency group snapshot? >>>> >>>> The easiest solution would be to remove all snapshots that are in >>>> GroupSnapshotNamespace and reference this consistency group. >>>> I looked into cinder docs for this feature: >>>> http://docs.openstack.org/admin-guide/blockstorage-consistency-groups.html >>>> >>>> But it's not clear to me which behavior cinder expects. >>>> >>>> Thanks, >>>> V. >>>> >>>> On Wed, Oct 26, 2016 at 6:16 AM, Jason Dillaman <jdillama@xxxxxxxxxx> wrote: >>>>> In a perfect world, it would be nice to add a new optional to "rbd >>>>> snap ls" to show all snapshots (with a new column to indicate the >>>>> associated namespace). >>>>> >>>>> On Tue, Oct 25, 2016 at 11:07 PM, Victor Denisov <vdenisov@xxxxxxxxxxxx> wrote: >>>>>> Question. When we print out snapshots of an image, should the group >>>>>> snapshots be listed, or should they be marked as special snapshots? >>>>>> >>>>>> Thanks, >>>>>> V. >>>>>> >>>>>> On Mon, Oct 10, 2016 at 3:14 PM, Victor Denisov <vdenisov@xxxxxxxxxxxx> wrote: >>>>>>> Ok. I didn't have any intention to throw exceptions. >>>>>>> I was more concerned about whether it's ok to allocate and delete >>>>>>> objects or I should use smart pointers. >>>>>>> >>>>>>> On Mon, Oct 10, 2016 at 7:18 AM, Jason Dillaman <jdillama@xxxxxxxxxx> wrote: >>>>>>>> The only place exceptions are routinely used is within the "::decode" >>>>>>>> functions. I would prefer to see the code not throwing new exceptions >>>>>>>> on purpose. >>>>>>>> >>>>>>>> On Fri, Oct 7, 2016 at 2:26 PM, Victor Denisov <vdenisov@xxxxxxxxxxxx> wrote: >>>>>>>>> Are any exceptions used in librbd code? Should the code be exception safe? >>>>>>>>> >>>>>>>>> Thanks, >>>>>>>>> V. >>>>>>>>> >>>>>>>>> On Fri, Sep 16, 2016 at 10:37 AM, Jason Dillaman <jdillama@xxxxxxxxxx> wrote: >>>>>>>>>> On Thu, Sep 15, 2016 at 7:17 PM, Victor Denisov <vdenisov@xxxxxxxxxxxx> wrote: >>>>>>>>>>> if (struct_v >= 5) { >>>>>>>>>>> ::decode(snapshot_namespace, p); >>>>>>>>>>> } else { >>>>>>>>>>> snapshot_namespace = cls::rbd::UserSnapshotNamespace(); >>>>>>>>>>> } >>>>>>>>>>> >>>>>>>>>>> then code for ::encode function of cls_rbd_snap would change accordingly: >>>>>>>>>>> >>>>>>>>>>> instead of >>>>>>>>>>> >>>>>>>>>>> boost::apply_visitor(cls::rbd::EncodeSnapshotTypeVisitor(bl), >>>>>>>>>>> snapshot_namespace); >>>>>>>>>>> >>>>>>>>>>> I would do: >>>>>>>>>>> ::encode(snapshot_namespace, bl); >>>>>>>>>> >>>>>>>>>> >>>>>>>>>> +1 -- looks good to me >>>>>>>>>> >>>>>>>>>> -- >>>>>>>>>> Jason >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> -- >>>>>>>> Jason >>>>> >>>>> >>>>> >>>>> -- >>>>> Jason >>> >>> >>> >>> -- >>> Jason >> >> >> >> -- >> Jason -- Jason -- 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
