Merge "outlet Temperature based migration strategy spec"

specs/mitaka/approved/outlet-temperature-based-strategy.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
+
+==========================================
+Outlet Temperature Based Strategy
+==========================================
+
+https://blueprints.launchpad.net/watcher/+spec/outlet-temperature-based-strategy
+
+Outlet(Exhaust Air) temperature is a new thermal telemetry which can be used
+to measure the server's thermal/workload status.
+
+This spec proposes a new Watcher migration strategy based on the outlet
+temperature of servers. This strategy makes decisions to migrate workloads
+to the servers with good thermal condition (lowest outlet temperature) when
+the outlet temperature of source servers reach a configurable threshold.
+
+Note: "server" in this document means "hypervisor".
+
+Problem description
+===================
+
+In current Data Center infrastructure, the cooling air supply to servers can
+be different. When a server is overloaded or the supply air is too hot, the
+outlet temperature telemetry can be used to detect the problem. In order to
+have the server in a reliable thermal condition, some of the server's
+workloads should be migrated to other server with safer thermal conditions.
+
+Use Cases
+----------
+
+As an administrator, I want to be able to trigger an audit that controls the
+temperature and perform workload load balancing.
+
+In order to :
+
+* Reduce the total power consumption spent on cooling.
+
+* Increase the lifespan of the data center because cooling effectiveness is a
+  first order factor.
+
+Project Priority
+-----------------
+
+Not relevant because Watcher is not in the big tent so far.
+
+Proposed change
+===============
+
+Watcher already has its decision framework, so this strategy should be a new
+class which extend the base strategy class.
+
+* Set the threshold in 2 steps : hard coded first, then through the template.
+
+* Create a new Python class to extend the "BaseStrategy" class.
+
+* Use the Ceilometer client to get Outlet temperature metrics of hypervisors.
+
+* Use the Nova objects framework to get free CPU/Memory/Disk of hypervisors.
+
+* An algorithm to detect if the threshold of Outlet temperature has been
+  reached and to choose the migration target server. It will filter the viable
+  targets according to the free resource information of hypervisors from
+  previous step.
+
+
+Alternatives
+------------
+
+No alternative
+
+Data model impact
+-----------------
+
+None
+
+REST API impact
+---------------
+
+None
+
+Security impact
+---------------
+
+None
+
+Notifications impact
+--------------------
+
+None
+
+Other end user impact
+---------------------
+
+None
+
+Performance Impact
+------------------
+
+There used to be some performance issues regarding the query of metrics from
+the Ceilometer database. This is one of the reason why it was rarely used in
+production environment. These issues may now be solved thanks to an
+abstraction layer which enables anybody to change the underlying metrics
+storage backend easily.
+There is also a performance issue when you query the Nova DB to get cpu
+usage metrics.
+
+Other deployer impact
+---------------------
+
+None
+
+Developer impact
+----------------
+
+None
+
+
+Implementation
+==============
+
+Assignee(s)
+-----------
+
+Primary assignee:
+  <junjie-huang>
+
+
+Work Items
+----------
+
+1. function to use Ceilometer client to get outlet temperature of hypervisors.
+
+2. function to filter servers by Nova basic metrics(free CPU/Memory/Disk)
+
+3. Rewrite execute function to add the algorithm to detect if the threshold
+   of outlet T has been reached and choose the target hypervisor, generate
+   action plan.
+
+
+Dependencies
+============
+
+* https://wiki.openstack.org/wiki/Ceilometer/blueprints/APIv2
+
+* https://blueprints.launchpad.net/ceilometer/+spec/api-v2-improvement
+
+* http://docs.openstack.org/admin-guide-cloud/telemetry-measurements.html
+
+* http://docs.openstack.org/developer/python-novaclient/api.html
+
+
+Testing
+=======
+
+Unit tests and functional test, will use a fake metrics set for running
+functional test.
+
+
+Documentation Impact
+====================
+
+A documentation explaining how to use this new optimization strategy.
+
+
+References
+==========
+
+http://www.intel.com/content/www/us/en/servers/ipmi/ipmi-home.html
+
+
+History
+=======
+
+None