Hi Xing, One more question. You mentioned that there is an operation: create consistency group from a snap shot. Does it mean that an image can be a member of several consistency groups?
Thanks, V. On Tue, Nov 8, 2016 at 6:21 AM, yang, xing <xing.y...@dell.com> wrote: > You cannot remove a volume completely if there is still a group snapshot. > You can remove the volume from the group but you can’t delete the volume > because it still has snapshot dependent on it. So if you want to completely > remove a volume that is in a group, you can delete the group snapshot first > which will delete the individual snapshot. After that you can remove the > volume from the group and delete the volume. > > More comments inline below. > > Thanks, > Xing > > > ________________________________________ > From: Victor Denisov [vdeni...@mirantis.com] > Sent: Tuesday, November 8, 2016 12:04 AM > To: OpenStack Development Mailing List (not for usage questions) > Cc: Jason Dillaman > Subject: Re: [openstack-dev] [cinder] consistency groups in ceph > > One more question. What is the expected behavior if you remove a > volume completely? > [Xing] You cannot remove the volume completely (delete volume won't succeed) > if there is still a group snapshot. > > Should the group snapshot removed first? Should the volume snapshot be > removed from the group snapshot? > [Xing] Yes, you should delete the group snapshot first and that will delete > the volume snapshot as well. > > Should we keep the snapshot even if the image doesn't exist anymore? > [Xing] You cannot delete the image (volume) if there is still a snapshot. > > Thanks, > Victor. > > On Tue, Nov 1, 2016 at 7:02 AM, yang, xing <xing.y...@dell.com> wrote: >> Hi Victor, >> >> Please see my answers inline below. >> >> In Newton, we added support for Generic Volume Groups. See doc below. CGs >> will be migrated to Generic Volume Groups gradually. Drivers should not >> implement CGs any more. Instead, it can add CG support using Generic Volume >> Group interfaces. I'm working on a dev doc to explain how to do this and >> will send an email to the mailing list when I'm done. The Generic Volume >> Group interface is very similar to CG interface, except that the Generic >> Volume Group requires an additional Group Type parameter to be created. >> Using Group Type, CG can be a special type of Generic Volume Group. Please >> feel free to grab me on Cinder IRC if you have any questions. My IRC handle >> is xyang or xyang1. >> >> http://docs.openstack.org/admin-guide/blockstorage-groups.html >> >> Thanks, >> Xing >> >> >> ________________________________________ >> From: Victor Denisov [vdeni...@mirantis.com] >> Sent: Monday, October 31, 2016 11:29 PM >> To: openstack-dev@lists.openstack.org >> Cc: Jason Dillaman >> Subject: [openstack-dev] [cinder] consistency groups in ceph >> >> Hi, >> >> I'm working on consistency groups feature in ceph. >> My question is about what kind of behavior does cinder expect from >> storage backends. >> I'm particularly interested in what happens to consistency groups >> snapshots when I remove an image from the group: >> >> Let's imagine I have a consistency group called CG. I have images in >> the consistency group: >> Im1, Im2, Im3, Im4. >> Let's imagine we have snapshots of this consistency group: >> >> CGSnap1 >> CGSnap2 >> CGSnap3 >> >> Snapshots of individual images in a consistency group snapshot I will call >> CGSnap2Im1 - Snapshot of image 1 from consistency group snapshot 2. >> >> Qustion 1: >> If consistency group CG has 4 images: Im1, Im2, Im3, Im4. >> Can CGSnap1 have more images than it already has: Im1, Im2, Im3, Im4, Im5. >> >> Can CGSnap1 have less images than it already has: Im1, Im2, Im3. >> >> [Xing] Once a snapshot is taken from a CG, it can no longer be changed. It >> is a point-in-time copy. CGSnap1 cannot be modified. >> >> Question 2: >> If we remove image2 from the consistency group. Does it mean that >> snapshots of this image should be removed from all the CGSnaps. >> >> Example: >> We are removing Im2. >> CGSnaps look like this: >> >> CGSnap1 - CGSnap1Im1, CGSnap1Im2, CGSnap1Im3 >> CGSnap2 - CGSnap2Im1, CGSnap2Im2, CGSnap2Im3, CGSnap3Im4 >> CGSnap3 - CGSnap3Im1, CGSnap3Im2, CGSnap3Im3, CGSnap3Im4 >> >> What happens to snapshots: CGSnap1Im2,CGSnap2Im2, CGSnap3Im2? Do we >> remove them, do we keep them. Is it important what we do to them at >> all? >> >> [Xing] If your CG contains 4 volumes when you take the snapshot of the CG, >> the resulting CGSnap should be associated with 4 snapshots corresponding to >> the 4 volumes. If you add more volumes to the CG or remove volumes from CG >> after CGSnap was taken, it should not affect CGSnap. It will only affect CG >> snapshots that you take in the future. >> >> Thanks, >> Victor. >> >> __________________________________________________________________________ >> OpenStack Development Mailing List (not for usage questions) >> Unsubscribe: openstack-dev-requ...@lists.openstack.org?subject:unsubscribe >> http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev >> __________________________________________________________________________ >> OpenStack Development Mailing List (not for usage questions) >> Unsubscribe: openstack-dev-requ...@lists.openstack.org?subject:unsubscribe >> http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev > > __________________________________________________________________________ > OpenStack Development Mailing List (not for usage questions) > Unsubscribe: openstack-dev-requ...@lists.openstack.org?subject:unsubscribe > http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev > __________________________________________________________________________ > OpenStack Development Mailing List (not for usage questions) > Unsubscribe: openstack-dev-requ...@lists.openstack.org?subject:unsubscribe > http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev __________________________________________________________________________ OpenStack Development Mailing List (not for usage questions) Unsubscribe: openstack-dev-requ...@lists.openstack.org?subject:unsubscribe http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev
