Capacity-based QoS

Blueprint: capacity-based-qos

Change-Id: I8e753320e1405721286ea4bbad9bbdfdfc025c9c

specs/pike/capacity_based_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
+
+==========================================
+Capacity-based QoS
+==========================================
+
+Include the URL of your launchpad blueprint:
+
+https://blueprints.launchpad.net/cinder/+spec/capacity-based-qos
+
+QoS values in Cinder currently are able to be set to static
+values.  This work proposes a way to derive QoS limit values
+based on volume capacities rather than static values.
+
+
+Problem description
+===================
+
+This proposes a mechanism to provision IOPS on a per-volume basis with
+the IOPS values adjusted based on the volume's size.  (IOPS per GB)
+
+
+Use Cases
+=========
+
+A deployer wishes to cap "usage" of this system to limits based
+on space usage as well as throughput, in order to bill customers
+and not exceed limits of the backend.
+
+Associating IOPS and size allows you to provide tiers such as
+
+ Gold:    1000 GB at 10000 IOPS per GB
+ Silver:  1000 GB at 5000 IOPS per GB
+ Bronze:   500 GB at 5000 IOPS per GB
+
+
+Proposed change
+===============
+
+Allow creation of qos_keys:
+   read_iops_sec_per_gb
+   write_iops_sec_per_gb
+   total_iops_sec_per_gb
+
+These function the same as our current <x>_iops_sec keys,
+except they are scaled by the volume size.
+
+
+Alternatives
+------------
+
+None
+
+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
+---------------------
+
+New optional qos spec values.
+
+Off by default, opt-in.
+
+Developer impact
+----------------
+
+None
+
+
+Implementation
+==============
+
+
+Assignee(s)
+-----------
+
+Primary assignee:
+  eharney
+
+
+Work Items
+----------
+
+* https://review.openstack.org/#/c/447127/
+
+
+Dependencies
+============
+
+
+Testing
+=======
+
+
+Documentation Impact
+====================
+
+Document new fields available in qos types.
+
+
+References
+==========
+
+Code: https://review.openstack.org/#/c/447127/