IBM SVC: Logging error when failed to create SVC host

[Rajat Dhasmana]

When attaching a volume created in IBM SVC storage, we create a SVC host with the following command[1][2][3]

svctask mkhost -force -iscsiname <IQN> -name <host>

If the SVC host already exists, we fail the command and try to use the existing host[4]

The problem with this workflow is, even if the SVC host creation fails due to an existing SVC host, it's not an actual failure but we still log an error[5] in this case which is misleading.

The error is logged from a generic method which runs ssh commands but we need to distinguish which failures are actual failures and which are not to help operators better debug the issues.

Also we already log an error if the make host fails for any other reason[6]

In summary, the ERROR message is misleading in this case and should not be logged in the above described case.

[1] https://opendev.org/openstack/cinder/src/commit/95630360b2091409dc35eebd86d51d9aad2ab0fc/cinder/volume/drivers/ibm/storwize_svc/storwize_svc_iscsi.py#L189-L192

[2] https://opendev.org/openstack/cinder/src/commit/95630360b2091409dc35eebd86d51d9aad2ab0fc/cinder/volume/drivers/ibm/storwize_svc/storwize_svc_common.py#L1505

[3] https://opendev.org/openstack/cinder/src/commit/95630360b2091409dc35eebd86d51d9aad2ab0fc/cinder/volume/drivers/ibm/storwize_svc/storwize_svc_common.py#L284

[4] https://opendev.org/openstack/cinder/src/commit/95630360b2091409dc35eebd86d51d9aad2ab0fc/cinder/volume/drivers/ibm/storwize_svc/storwize_svc_iscsi.py#L194-L199

[5] https://opendev.org/openstack/cinder/src/commit/95630360b2091409dc35eebd86d51d9aad2ab0fc/cinder/volume/drivers/ibm/storwize_svc/storwize_svc_common.py#L3686-L3687

[6] https://opendev.org/openstack/cinder/src/commit/95630360b2091409dc35eebd86d51d9aad2ab0fc/cinder/volume/drivers/ibm/storwize_svc/storwize_svc_iscsi.py#L201-L203