use copy-on-write for all volume cloning

Registered by Edward Hope-Morley on 2013-08-09

clone from snapshot currenlty uses copy-on-write but clone from volume does not (currently does a full copy). Let's see if we can find a solution to this.

Blueprint information

Status:
Complete
Approver:
John Griffith
Priority:
Low
Drafter:
Edward Hope-Morley
Direction:
Approved
Assignee:
Edward Hope-Morley
Definition:
Approved
Series goal:
Accepted for havana
Implementation:
Implemented
Milestone target:
milestone icon 2013.2
Started by
Edward Hope-Morley on 2013-08-09
Completed by
Edward Hope-Morley on 2013-09-06

Related branches

Sprints

Whiteboard

see bug #1209199 for discussions.

So proposed solutuion is as follows:

We will create a snapshot of the source volume from which to create our clone. If the source volume gets deleted it will be silently maintained until all clones/snapshots are deleted. We will allow for a (user-configurable) maximum of chained clones up to which we will enforce a flatten. This is will avoid excessively long clone chains which could lead to flatten storms and possibly performance issues.

Gerrit topic: https://review.openstack.org/#q,topic:bug/1209199,n,z

Addressed by: https://review.openstack.org/41469
    Added copy-on-write support for all RBD cloning

<jdg>
Missed the deadline, if you submit something tonight that addresses concerns we can probably get an exception but it seems like it's stuck for now.

FFE for Havana

(?)

Work Items

Work items:
IMPLEMENTATION: DONE

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