Or probably when we clone a consistency group from a snapshot we should clone all the images in this consistency group?
On Mon, Dec 5, 2016 at 3:15 PM, Victor Denisov <[email protected]> wrote: > 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 <[email protected]> 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 [[email protected]] >> 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 <[email protected]> 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 [[email protected]] >>> Sent: Monday, October 31, 2016 11:29 PM >>> To: [email protected] >>> 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: [email protected]?subject:unsubscribe >>> http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev >>> __________________________________________________________________________ >>> OpenStack Development Mailing List (not for usage questions) >>> Unsubscribe: [email protected]?subject:unsubscribe >>> http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev >> >> __________________________________________________________________________ >> OpenStack Development Mailing List (not for usage questions) >> Unsubscribe: [email protected]?subject:unsubscribe >> http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev >> __________________________________________________________________________ >> OpenStack Development Mailing List (not for usage questions) >> Unsubscribe: [email protected]?subject:unsubscribe >> http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev __________________________________________________________________________ OpenStack Development Mailing List (not for usage questions) Unsubscribe: [email protected]?subject:unsubscribe http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev
