openstack/cinder-specs
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cinder-specs/specs/juno/cinder-storwize-driver-qos.rst
zhangbailin 456b86528d Modify spelling mistakes 
When I read this specs file, I found a lot of spelling mistakes,
and I made a change here to give you a good code reading experience.

In specs, modify "acording" to "according" and  "priviledges" to
"privileges" and "Additionaly" to "Additionally" and so on. you can
get them from the "File Path" in the web.

Change-Id: I95228e1a57c7aa588c78d4a3af46b18daadac01d
2017-08-14 17:55:30 -07:00

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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.

Use Cases

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.

Other end user 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 according 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