OpenStack Shared File Systems Service (Manila)

NetApp cDOT driver should not split clone from snapshot after creation

Bug #1554592 reported by Clinton Knight on 2016-03-08

This bug affects 2 people

Affects		Status	Importance	Assigned to	Milestone
	OpenStack Shared File Systems Service (Manila)	Fix Released	Low	Clinton Knight	OpenStack Shared File Systems Service (Manila) mitaka-rc1 "RC1"

Bug Description

An earlier bug (https://bugs.launchpad.net/manila/+bug/1259988 "NetApp cDOT driver should split clone from snapshot after creation") led us to modify the NetApp cDOT driver to split cloned shares off from their parents immediately upon creation. As described in that bug report, the fix makes the source snapshot deletable after the clone split is done. However, the more significant negative consequence is that the storage efficiency gains from having cloned the blocks are lost. We have had customer complaints who expect to retain the storage efficiency of cDOT snapshots and cloning.

The fix is to not start a clone split during the create-from-snapshot workflow. Instead, if/when a request to delete the locked snapshot is received, the driver should start the clone split at that time and soft-delete the snapshot. The driver already has logic for reaping soft-deleted objects, so it is straightforward to also reap deleted snapshots as they become un-busy.

Tags:

Clinton Knight (clintonk) on 2016-03-08

Changed in manila:
status:	New → In Progress

Ben Swartzlander (bswartz) on 2016-03-08

Changed in manila:
milestone:	none → mitaka-rc1
importance:	Undecided → Low

Revision history for this message

OpenStack Infra (hudson-openstack) wrote on 2016-03-14: Fix proposed to manila (master)

Fix proposed to branch: master
Review: https://review.openstack.org/292528

Revision history for this message

OpenStack Infra (hudson-openstack) wrote on 2016-03-15: Fix merged to manila (master)

Reviewed: https://review.openstack.org/292528
Committed: https://git.openstack.org/cgit/openstack/manila/commit/?id=4a2290193c5401006fb130fd199759be8dbeba56
Submitter: Jenkins
Branch: master

commit 4a2290193c5401006fb130fd199759be8dbeba56
Author: Clinton Knight <email address hidden>
Date: Tue Mar 8 11:04:24 2016 -0500

NetApp cDOT driver should not split clones

    An earlier bug (https://bugs.launchpad.net/manila/+bug/1259988
    "NetApp cDOT driver should split clone from snapshot after
    creation") led us to modify the NetApp cDOT driver to split cloned
    shares off from their parents immediately upon creation. As
    described in that bug report, the fix makes the source snapshot
    deletable after the clone split is done. However, the more
    significant negative consequence is that the storage efficiency
    gains from having cloned the blocks are lost. We have had
    complaints from users who expect to retain the storage efficiency
    of cDOT snapshots and cloning.

    The fix is to not start a clone split during the
    create-from-snapshot workflow. Instead, if/when a request to
    delete the locked snapshot is received, the driver should start
    the clone split at that time and soft-delete the snapshot. The
    driver already has logic for reaping soft-deleted objects, so it
    is straightforward to also reap deleted snapshots as they become
    un-busy.

Change-Id: I0f7ba8f76dce6f55c64e156b372317387d299fa6
Closes-Bug: #1554592