Merge "Propose: Add QoS capability to the IBM Storwize driver"

specs/juno/cinder-storwize-driver-qos.rst

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+..
+ This work is licensed under a Creative Commons Attribution 3.0 Unported
+ License.
+
+ http://creativecommons.org/licenses/by/3.0/legalcode
+
+=============================================
+Add QoS capability to the IBM Storwize driver
+=============================================
+
+https://blueprints.launchpad.net/cinder/+spec/cinder-storwize-driver-qos
+
+Storwize driver can provide the QoS capability with the parameter of
+IO throttling, which caps the amount of I/O that is accepted. This
+blueprints proposes to add the QoS support for Storwize driver.
+
+Problem description
+===================
+
+Storwize backend storage can be enabled with the QoS support by limiting
+the amount of I/O for a specific volume. QoS has been implemented for
+some cinder storage drivers, and it is feasible for the storwize driver
+to add this feature as well.
+
+Proposed change
+===============
+
+To enable the QoS for storwize driver, an extra spec with IOThrottling as the
+key needs to bind to a volume type. All the following changes apply to the
+Storwize driver code.
+
+Create volume:
+
+* If QoS is enabled and IOThrottling is available as the QoS key, set the I/O
+  throttling of the volume into the specified IOThrottling value.
+
+Create clone volume:
+
+* If the QoS is set for the original volume, the target volume needs to set
+  to the same QoS.
+
+Create snapshot:
+
+* The QoS attributes will be copied to the snapshot.
+
+Create volume from snapshot:
+
+* If QoS is enabled and IOThrottling is available as the QoS key, set the IO
+  throttling of the volume into the specified IOThrottling value.
+
+Re-type volume:
+
+* If a volume type is changed, a different IOThrottling value will apply to
+  the volume and the I/O of the volume needs to be set to the new IO
+  throttling.
+
+
+Alternatives
+------------
+
+The proposed change follows the pattern, in which other drivers implement the
+QoS feature.
+
+Data model impact
+-----------------
+
+None.
+
+REST API impact
+---------------
+
+None.
+
+Security impact
+---------------
+
+None.
+
+Notifications impact
+--------------------
+
+None.
+
+Performance Impact
+------------------
+
+None.
+
+Other deployer impact
+---------------------
+
+The QoS for Storwize driver can be configurable with a configuration option
+in cinder.conf. An extra spec with the key of IOThrottling can bind to a
+volume type, so that the volumes with this volume type are guaranteed with
+an I/O throttling rate. 
+
+Developer impact
+----------------
+
+None.
+
+
+Implementation
+==============
+
+Assignee(s)
+-----------
+
+Primary assignee:
+  Vincent Hou
+
+Other contributors:
+  TBD
+
+Work Items
+----------
+
+* Add a configuration option to allow the user the use the QoS for Storwize
+  driver.
+* Add the QoS enablement check and set the I/O throttling in create volume.
+* Add the QoS enablement check and set the I/O throttling in create volume
+  from snapshot.
+* Set the I/O throttling to the new volume acording to the original volume
+  in create clone volume.
+* Copy the QoS attributes to the snapshot in create snapshot.
+* Change the I/O throttling of the volume if the volume type is changed.
+
+Dependencies
+============
+
+None.
+
+Testing
+=======
+
+* Unit tests need to be added to test the QoS for Storwize driver.
+
+Documentation Impact
+====================
+
+* Add how to configure the QoS for the Storwize driver in the document.
+
+References
+==========
+
+* Add QoS capability to the IBM storwize driver
+  https://blueprints.launchpad.net/cinder/+spec/cinder-storwize-driver-qos
+