Add zone migration strategy document

This patch set adds zone migration strategy document.

Change-Id: Ifd9d85d635977900929efd376f0d7990a6fec627

doc/source/strategies/zone_migration.rst

@@ -0,0 +1,154 @@
+==============
+Zone migration
+==============
+
+Synopsis
+--------
+
+**display name**: ``Zone migration``
+
+**goal**: ``hardware_maintenance``
+
+    .. watcher-term:: watcher.decision_engine.strategy.strategies.zone_migration
+
+Requirements
+------------
+
+Metrics
+*******
+
+None
+
+Cluster data model
+******************
+
+Default Watcher's Compute cluster data model:
+
+    .. watcher-term:: watcher.decision_engine.model.collector.nova.NovaClusterDataModelCollector
+
+Storage cluster data model is also required:
+
+    .. watcher-term:: watcher.decision_engine.model.collector.cinder.CinderClusterDataModelCollector
+
+Actions
+*******
+
+
+Default Watcher's actions:
+
+    .. list-table::
+       :widths: 30 30
+       :header-rows: 1
+
+       * - action
+         - description
+       * - ``migrate``
+         - .. watcher-term:: watcher.applier.actions.migration.Migrate
+       * - ``volume_migrate``
+         - .. watcher-term:: watcher.applier.actions.volume_migration.VolumeMigrate
+
+Planner
+*******
+
+Default Watcher's planner:
+
+    .. watcher-term:: watcher.decision_engine.planner.weight.WeightPlanner
+
+Configuration
+-------------
+
+Strategy parameters are:
+
+======================== ======== ============= ==============================
+parameter                type     default Value description
+======================== ======== ============= ==============================
+``compute_nodes``        array    None          Compute nodes to migrate.
+``storage_pools``        array    None          Storage pools to migrate.
+``parallel_total``       integer  6             The number of actions to be
+                                                run in parallel in total.
+``parallel_per_node``    integer  2             The number of actions to be
+                                                run in parallel per compute
+                                                node.
+``parallel_per_pool``    integer  2             The number of actions to be
+                                                run in parallel per storage
+                                                pool.
+``priority``             object   None          List prioritizes instances
+                                                and volumes.
+``with_attached_volume`` boolean  False         False: Instances will migrate
+                                                after all volumes migrate.
+                                                True: An instance will migrate
+                                                after the attached volumes
+                                                migrate.
+======================== ======== ============= ==============================
+
+The elements of compute_nodes array are:
+
+============= ======= =============== =============================
+parameter     type    default Value   description
+============= ======= =============== =============================
+``src_node``  string    None          Compute node from which
+                                      instances migrate(mandatory).
+``dst_node``  string    None          Compute node to which
+                                      instances migrate.
+============= ======= =============== =============================
+
+The elements of storage_pools array are:
+
+============= ======= =============== ==============================
+parameter     type    default Value   description
+============= ======= =============== ==============================
+``src_pool``  string    None          Storage pool from which
+                                      volumes migrate(mandatory).
+``dst_pool``  string    None          Storage pool to which
+                                      volumes migrate.
+``src_type``  string    None          Source volume type(mandatory).
+``dst_type``  string    None          Destination volume type
+                                      (mandatory).
+============= ======= =============== ==============================
+
+The elements of priority object are:
+
+================ ======= =============== ======================
+parameter        type    default Value   description
+================ ======= =============== ======================
+``project``      array   None            Project names.
+``compute_node`` array   None            Compute node names.
+``storage_pool`` array   None            Storage pool names.
+``compute``      enum    None            Instance attributes.
+                                         |compute|
+``storage``      enum    None            Volume attributes.
+                                         |storage|
+================ ======= =============== ======================
+
+.. |compute| replace:: ["vcpu_num", "mem_size", "disk_size", "created_at"]
+.. |storage| replace:: ["size", "created_at"]
+
+Efficacy Indicator
+------------------
+
+.. watcher-func::
+  :format: literal_block
+
+  watcher.decision_engine.goal.efficacy.specs.HardwareMaintenance.get_global_efficacy_indicator
+
+Algorithm
+---------
+
+For more information on the zone migration strategy please refer
+to: http://specs.openstack.org/openstack/watcher-specs/specs/queens/implemented/zone-migration-strategy.html
+
+How to use it ?
+---------------
+
+.. code-block:: shell
+
+    $ openstack optimize audittemplate create \
+      at1 hardware_maintenance --strategy zone_migration
+
+    $ openstack optimize audit create -a at1 \
+      -p compute_nodes='[{"src_node": "s01", "dst_node": "d01"}]'
+
+External Links
+--------------
+
+None