[Storwize] Retype of a non-rep mirror volume to mirror- volume-type with different mirror_pool is failing

[Mounika Sreeram]

On the SVC cinder driver, facing an issue while retyping a non_replication mirror volume(Local mirror copy) to a volume-type template with a different mirror_pool than the former one with which volume is being created.

ERROR cinder.volume.manager [req-5bac621a-80a4-46ad-9e73-eddbaafb60f9 req-eeeb5dfa-0ec9-4b25-8f18-f260d6345fb3 admin None] Volume 5ce4016d-079a-4b5b-a03d-011fffc69dd5: driver error when trying to retype, falling back to generic mechanism.: UnboundLocalError: local variable 'msg' referenced before assignment
ERROR cinder.volume.manager Traceback (most recent call last):
ERROR cinder.volume.manager File "/opt/stack/cinder/cinder/volume/manager.py", line 3039, in retype
ERROR cinder.volume.manager ret = self.driver.retype(context,
ERROR cinder.volume.manager File "/opt/stack/cinder/cinder/volume/drivers/ibm/storwize_svc/storwize_svc_common.py", line 5405, in retype
ERROR cinder.volume.manager self._verify_retype_params(volume, new_opts, old_opts, need_copy,
ERROR cinder.volume.manager File "/opt/stack/cinder/cinder/volume/drivers/ibm/storwize_svc/storwize_svc_common.py", line 5193, in _verify_retype_params
ERROR cinder.volume.manager raise exception.VolumeDriverException(message=msg)
ERROR cinder.volume.manager UnboundLocalError: local variable 'msg' referenced before assignment
ERROR cinder.volume.manager
ERROR oslo_messaging.rpc.server [req-5bac621a-80a4-46ad-9e73-eddbaafb60f9 req-eeeb5dfa-0ec9-4b25-8f18-f260d6345fb3 admin None] Exception during message handling: cinder.exception.VolumeMigrationFailed: Volume migration failed: Retype requires migration but is not allowed.

Steps to Reproduce:
1. Create two Non-replication mirror-volume-types with different mirror_pool spec value[Ex: mirror_volume_type_1 with mirror_pool = pool1, mirror_volume_type_2 with mirror_pool = pool2]
2. Create a Non-rep mirror volume(ex: non-rep-vol1) with the volume-type template 'mirror_volume_type1'
3. Retype the volume 'non-rep-vol1' to the volume-type template 'mirror_volume_type2'
4. Expected : Retype operation should be successful
   Actual result: Failing with UnboundLocalError: local variable 'msg' referenced before assignment

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.opendev.org/c/openstack/cinder/+/816324

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.opendev.org/c/openstack/cinder/+/816324
Committed: https://opendev.org/openstack/cinder/commit/50e173101162b32949bc51eba288c5b773cb9cb1
Submitter: "Zuul (22348)"
Branch: master

commit 50e173101162b32949bc51eba288c5b773cb9cb1
Author: Mounika Sreeram <email address hidden>
Date: Tue Nov 2 10:23:02 2021 +0000

    [SVF] Fix Retype issue of mirror volume

    [Spectrum Virtualize Family] Retype of mirror-volume to volume-type
    with different mirror-pool scenario is not working.

    When there is a change of mirror-pool in retype operation then it is
    checking whether source/target type has data reduction pool. If it
    contains data reduction pool, it will throw an exception. If not,
    it has to continue the retype operation with change of mirror pool.
    Due to the incorrect place of raising an exception for
    data-reduction pool,it is effecting the retype operation of
    volume-type with different mirror-pool.

    Updated the code to raise an exception correctly to fix this issue.

    Closes-Bug: #1949061
    Change-Id: I12018c3a1f6e4e59a4923ef81da85c2d7c74e96d

[OpenStack Infra (hudson-openstack)]

This issue was fixed in the openstack/cinder 20.0.0.0rc1 release candidate.