Zone migration

updated: 2019-04-01 01:33

Zone migration¶

Synopsis¶

display name: Zone migration

goal: hardware_maintenance

Zone migration using instance and volume migration

This is zone migration strategy to migrate many instances and volumes efficiently with minimum downtime for hardware maintenance.

Requirements¶

Metrics¶

None

Cluster data model¶

Default Watcher’s Compute cluster data model:

Nova cluster data model collector

The Nova cluster data model collector creates an in-memory representation of the resources exposed by the compute service.

Storage cluster data model is also required:

Cinder cluster data model collector

The Cinder cluster data model collector creates an in-memory representation of the resources exposed by the storage service.

Actions¶

Default Watcher’s actions:

action description
migrate
Migrates a server to a destination nova-compute host

This action will allow you to migrate a server to another compute destination host. Migration type ‘live’ can only be used for migrating active VMs. Migration type ‘cold’ can be used for migrating non-active VMs as well active VMs, which will be shut down while migrating.

The action schema is:
schema = Schema({
 'resource_id': str,  # should be a UUID
 'migration_type': str,  # choices -> "live", "cold"
 'destination_node': str,
 'source_node': str,
})
The resource_id is the UUID of the server to migrate. The source_node and destination_node parameters are respectively the source and the destination compute hostname (list of available compute hosts is returned by this command: nova service-list --binary nova-compute).
volume_migrate
Migrates a volume to destination node or type

By using this action, you will be able to migrate cinder volume. Migration type ‘swap’ can only be used for migrating attached volume. Migration type ‘migrate’ can be used for migrating detached volume to the pool of same volume type. Migration type ‘retype’ can be used for changing volume type of detached volume.

The action schema is:
schema = Schema({
    'resource_id': str,  # should be a UUID
    'migration_type': str,  # choices -> "swap", "migrate","retype"
    'destination_node': str,
    'destination_type': str,
})
The resource_id is the UUID of cinder volume to migrate. The destination_node is the destination block storage pool name. (list of available pools are returned by this command: cinder get-pools) which is mandatory for migrating detached volume to the one with same volume type. The destination_type is the destination block storage type name. (list of available types are returned by this command: cinder type-list) which is mandatory for migrating detached volume or swapping attached volume to the one with different volume type.

action	description
`migrate`	Migrates a server to a destination nova-compute host This action will allow you to migrate a server to another compute destination host. Migration type ‘live’ can only be used for migrating active VMs. Migration type ‘cold’ can be used for migrating non-active VMs as well active VMs, which will be shut down while migrating. The action schema is: schema = Schema({ 'resource_id': str, # should be a UUID 'migration_type': str, # choices -> "live", "cold" 'destination_node': str, 'source_node': str, }) The resource_id is the UUID of the server to migrate. The source_node and destination_node parameters are respectively the source and the destination compute hostname (list of available compute hosts is returned by this command: `nova service-list --binary nova-compute`).
`volume_migrate`	Migrates a volume to destination node or type By using this action, you will be able to migrate cinder volume. Migration type ‘swap’ can only be used for migrating attached volume. Migration type ‘migrate’ can be used for migrating detached volume to the pool of same volume type. Migration type ‘retype’ can be used for changing volume type of detached volume. The action schema is: schema = Schema({ 'resource_id': str, # should be a UUID 'migration_type': str, # choices -> "swap", "migrate","retype" 'destination_node': str, 'destination_type': str, }) The resource_id is the UUID of cinder volume to migrate. The destination_node is the destination block storage pool name. (list of available pools are returned by this command: `cinder get-pools`) which is mandatory for migrating detached volume to the one with same volume type. The destination_type is the destination block storage type name. (list of available types are returned by this command: `cinder type-list`) which is mandatory for migrating detached volume or swapping attached volume to the one with different volume type.

Planner¶

Default Watcher’s planner:

Weight planner implementation

This implementation builds actions with parents in accordance with weights. Set of actions having a higher weight will be scheduled before the other ones. There are two config options to configure: action_weights and parallelization.

Limitations

This planner requires to have action_weights and parallelization configs tuned well.

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. [“vcpu_num”, “mem_size”, “disk_size”, “created_at”]
`storage`	enum	None	Volume attributes. [“size”, “created_at”]

Efficacy Indicator¶

[{'value': 0, 'name': 'live_instance_migrate_ratio', 'unit': '%', 'description': u'Ratio of actual live migrated instances to planned live migrate instances.'}, {'value': 0, 'name': 'cold_instance_migrate_ratio', 'unit': '%', 'description': u'Ratio of actual cold migrated instances to planned cold migrate instances.'}, {'value': 0, 'name': 'volume_migrate_ratio', 'unit': '%', 'description': u'Ratio of actual detached volumes migrated to planned detached volumes migrate.'}, {'value': 0, 'name': 'volume_update_ratio', 'unit': '%', 'description': u'Ratio of actual attached volumes migrated to planned attached volumes migrate.'}]

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 ?¶

$ 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¶