03073a1b0d
In a recent patch [1], a bug in the zone migration strategy was fixed, which prevented audits using this strategy to create action plans with both instance and volume migrations. We documented this limitation, but forgot to remove the note when fixing this bug. [1] https://review.opendev.org/c/openstack/watcher/+/952115 Change-Id: I2074f2b911dfcbf44716ff30d8ea35a5046b8520 Signed-off-by: jgilaber <jgilaber@redhat.com>
207 lines
7.8 KiB
ReStructuredText
207 lines
7.8 KiB
ReStructuredText
==============
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Zone migration
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==============
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Synopsis
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--------
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**display name**: ``Zone migration``
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**goal**: ``hardware_maintenance``
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.. watcher-term:: watcher.decision_engine.strategy.strategies.zone_migration.ZoneMigration
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.. note::
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The term ``Zone`` in the strategy name is not a reference to
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`Openstack availability zones <https://docs.openstack.org/nova/latest/admin/availability-zones.html>`_
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but rather a user-defined set of Compute nodes and storage pools.
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Currently, migrations across actual availability zones is not fully tested
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and might not work in all cluster configurations.
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Requirements
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------------
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Metrics
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*******
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None
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Cluster data model
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******************
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Default Watcher's Compute cluster data model:
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.. watcher-term:: watcher.decision_engine.model.collector.nova.NovaClusterDataModelCollector
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Storage cluster data model is also required:
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.. watcher-term:: watcher.decision_engine.model.collector.cinder.CinderClusterDataModelCollector
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Actions
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*******
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Default Watcher's actions:
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.. list-table::
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:widths: 30 30
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:header-rows: 1
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* - action
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- description
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* - ``migrate``
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- .. watcher-term:: watcher.applier.actions.migration.Migrate
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* - ``volume_migrate``
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- .. watcher-term:: watcher.applier.actions.volume_migration.VolumeMigrate
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Planner
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*******
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Default Watcher's planner:
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.. watcher-term:: watcher.decision_engine.planner.weight.WeightPlanner
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Configuration
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-------------
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Strategy parameters are:
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======================== ======== ======== ========= ==========================
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parameter type default required description
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======================== ======== ======== ========= ==========================
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``compute_nodes`` array None Optional Compute nodes to migrate.
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``storage_pools`` array None Optional Storage pools to migrate.
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``parallel_total`` integer 6 Optional The number of actions to
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be run in parallel in
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total.
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``parallel_per_node`` integer 2 Optional The number of actions to
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be run in parallel per
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compute node in one
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action plan.
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``parallel_per_pool`` integer 2 Optional The number of actions to
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be run in parallel per
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storage pool.
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``priority`` object None Optional List prioritizes instances
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and volumes.
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``with_attached_volume`` boolean False Optional False: Instances will
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migrate after all volumes
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migrate.
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True: An instance will
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migrate after the
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attached volumes migrate.
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======================== ======== ======== ========= ==========================
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.. note::
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* All parameters in the table above have defaults and therefore the
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user can create an audit without specifying a value. However,
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if **only** defaults parameters are used, there will be nothing
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actionable for the audit.
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* ``parallel_*`` parameters are not in reference to concurrency,
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but rather on limiting the amount of actions to be added to the action
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plan
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* ``compute_nodes``, ``storage_pools``, and ``priority`` are optional
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parameters, however, if they are passed they **require** the parameters
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in the tables below:
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The elements of compute_nodes array are:
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============= ======= ======== ========= ========================
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parameter type default required description
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============= ======= ======== ========= ========================
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``src_node`` string None Required Compute node from which
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instances migrate.
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``dst_node`` string None Optional Compute node to which
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instances migrate.
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If omitted, nova will
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choose the destination
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node automatically.
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============= ======= ======== ========= ========================
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The elements of storage_pools array are:
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============= ======= ======== ========= ========================
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parameter type default required description
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============= ======= ======== ========= ========================
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``src_pool`` string None Required Storage pool from which
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volumes migrate.
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``dst_pool`` string None Optional Storage pool to which
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volumes migrate.
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``src_type`` string None Optional Source volume type.
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``dst_type`` string None Required Destination volume type
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============= ======= ======== ========= ========================
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The elements of priority object are:
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================ ======= ======== ========= =====================
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parameter type default Required description
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================ ======= ======== ========= =====================
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``project`` array None Optional Project names.
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``compute_node`` array None Optional Compute node names.
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``storage_pool`` array None Optional Storage pool names.
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``compute`` enum None Optional Instance attributes.
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|compute|
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``storage`` enum None Optional Volume attributes.
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|storage|
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================ ======= ======== ========= =====================
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.. |compute| replace:: ["vcpu_num", "mem_size", "disk_size", "created_at"]
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.. |storage| replace:: ["size", "created_at"]
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Efficacy Indicator
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------------------
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The efficacy indicators for action plans built from the command line
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are:
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.. watcher-func::
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:format: literal_block
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watcher.decision_engine.goal.efficacy.specs.HardwareMaintenance.get_global_efficacy_indicator
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In **Horizon**, these indictors are shown with alternative text.
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* ``live_migrate_instance_count`` is shown as
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``The number of instances actually live migrated`` in Horizon
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* ``planned_live_migrate_instance_count`` is shown as
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``The number of instances planned to live migrate`` in Horizon
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* ``planned_live_migration_instance_count`` refers to the instances planned
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to live migrate in the action plan.
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* ``live_migrate_instance_count`` tracks all the instances that could be
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migrated according to the audit input.
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Algorithm
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---------
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For more information on the zone migration strategy please refer
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to: http://specs.openstack.org/openstack/watcher-specs/specs/queens/implemented/zone-migration-strategy.html
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How to use it ?
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---------------
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.. code-block:: shell
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$ openstack optimize audittemplate create \
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at1 hardware_maintenance --strategy zone_migration
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$ openstack optimize audit create -a at1 \
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-p compute_nodes='[{"src_node": "s01", "dst_node": "d01"}]'
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.. note::
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* The Cinder model collector is not enabled by default.
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If the Cinder model collector is not enabled while deploying Watcher,
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the model will become outdated and cause errors eventually.
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See the `Configuration option to enable the storage collector <https://docs.openstack.org/watcher/latest/configuration/watcher.html#collector.collector_plugins>`_ documentation.
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Support caveats
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---------------
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This strategy offers the option to perform both Instance migrations and
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Volume migrations. Currently, Instance migrations are ready for production
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use while Volume migrations remain experimental.
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External Links
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--------------
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None
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