3PAR image cache fails

[Walt Boring]

The new generic image cache capability in Cinder doesn't work with 3PAR.

The 3PAR volume driver's clone implementation does a background clone on the array. When a volume is being cloned, it can be attached and IO can be written to it. Unfortunately, you can't extend a volume that's being cloned, which is what the generic image cache does.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/219406

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/219406
Committed: https://git.openstack.org/cgit/openstack/cinder/commit/?id=1fccdfb7950d0c40ef99f62df47344f3e890dacf
Submitter: Jenkins
Branch: master

commit 1fccdfb7950d0c40ef99f62df47344f3e890dacf
Author: Walter A. Boring IV <email address hidden>
Date: Tue Sep 1 11:59:22 2015 -0700

    3PAR Disable generic image volume cache

    This patch disables the 3PAR drivers if an admin tries to
    enable the generic image volume cache capability.

    The 3PAR drivers don't work with this currently because of the way volume
    cloning works in the drivers. When a volume is cloned, it's done so
    in the background, which makes the clone available immediately for attaching.
    The problem is, a background cloning also locks the original volume from
    being modified. The generic image cache does a clone, and then an extend
    volume, which fails for the 3PAR drivers currently.

    Change-Id: If2e79a24969ab85bacdffdf750af5fc74be37a5c
    Partial-Bug: 1491088

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/236143
Committed: https://git.openstack.org/cgit/openstack/cinder/commit/?id=ab573d0412df807eaf129ab6c2af47dba02e1de7
Submitter: Jenkins
Branch: master

commit ab573d0412df807eaf129ab6c2af47dba02e1de7
Author: Walter A. Boring IV <email address hidden>
Date: Thu Sep 10 11:19:24 2015 -0700

    3PAR fix driver to work with image cache

    This patch fixes the problem with the 3PAR not
    working with the generic image cache.

    In order to do the image cache, the 3PAR has to create a
    temporary snapshot of the volume being cloned. Then the
    background cloning is against the temporary snapshot.
    The problem is, the temporary snapshot stays around.
    We try to account for this temporary snapshot in
    the delete volume action.

    We also bump the minimum required python-3parclient
    version to 4.1.0, which has the new getVolumeSnapshots
    API call required to make this all work.

    Change-Id: I6dea01ce07387990aa38bd5106b51504739b3a6e
    Closes-Bug: #1491088

[Doug Hellmann (doug-hellmann)]

This issue was fixed in the openstack/cinder 8.0.0.0b3 development milestone.