243 lines
5.9 KiB
ReStructuredText
243 lines
5.9 KiB
ReStructuredText
.. -*- rst -*-
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=================================
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Share Migration (since API v2.22)
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=================================
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The Share Migration API is an administrator-only experimental API that allows
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the invoker to select a destination pool to migrate a share to,
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while still allowing clients to access the source
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"share instance" during migration.
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Share migration is implemented in a 2-phase approach. The first phase of
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migration is when operations that take the longest are performed, such as
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data copying or replication. After first phase of data copying is complete,
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it is up to administrator to trigger the second phase,
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often referred to as switchover phase, which may perform operations
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such as final sync and deleting the source share instance.
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During the data copy phase, user can remain connected to the source, and may have
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to reconnect after the switchover phase. In order to migrate a share, manila
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may employ one of two mechanisms which are driver-assisted migration and
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host-assisted migration.
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- ``Driver-assisted migration``: This mechanism is intended to make use of driver
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optimizations to migrate shares between pools of the same storage vendor.
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This mechanism allows migrating shares nondisruptively while the source
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remains writable, preserving all filesystem metadata and snapshots.
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The migration workload is performed in the storage back end.
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- ``Host-assisted migration``: This mechanism is intended to migrate
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shares in an agnostic manner between two different pools, regardless
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of storage vendor. The implementation for this mechanism does not
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offer the same properties found in driver-assisted migration.
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In host-assisted migration, the source remains readable,
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snapshots must be deleted prior to starting the migration,
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filesystem metadata may be lost, and the clients will get
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disconnected by the end of migration. The migration workload
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is performed by the Data Service, which is a dedicated
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manila service for intensive data operations.
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These methods provide different capabilities
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and affect how efficiently the data copy and switchover
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are achieved. Generally speaking, driver-assisted migration is
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limited to homogenous storage backends and when available,
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is expected to be faster and more efficient than host-assisted migration.
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Driver-assisted migration occurs on the storage backend,
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while host-assisted migration occurs on the OpenStack nodes
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running the manila data service.
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When starting a migration, ``driver-assisted migration`` is
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attempted first. If the shared file system service detects
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it is not possible to perform the ``driver-assisted
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migration``, it proceeds to attempt
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``host-assisted migration``.
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Possible use cases for data migration include:
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- Migrating shares along with snapshots.
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- Bring down a physical storage device for maintenance
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- Free up space in a thinly-provisioned back end.
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- Load balancing among share servers.
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- Retyping a share
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.. note::
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Share Migration APIs are `experimental APIs <#experimental-apis>`_ .
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Start Migration
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===============
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.. rest_method:: POST /v2/{project_id}/shares/{share_id}/action
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.. versionadded:: 2.22
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Initiates share migration. This API will initiate the share data copy to the
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new host. The copy operation is non-disruptive.
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Response codes
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--------------
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.. rest_status_code:: success status.yaml
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- 202
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.. rest_status_code:: error status.yaml
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- 400
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- 401
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- 403
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- 404
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- 409
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Request
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-------
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.. rest_parameters:: parameters.yaml
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- project_id: project_id
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- share_id: share_id
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- force_host_assisted_migration: force_host_assisted_migration
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- preserve_snapshots: preserve_snapshots
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- preserve_metadata: preserve_metadata
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- nondisruptive: nondisruptive
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- writable: writable
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- new_share_type_id: new_share_type_id
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- new_share_network_id: new_share_network_id
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- host: host
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Request example
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---------------
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.. literalinclude:: samples/share-migration-start-request.json
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:language: javascript
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Complete Migration
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==================
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.. rest_method:: POST /v2/{project_id}/shares/{share_id}/action
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.. versionadded:: 2.22
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Completes share migration. This API will initiate the switch-over from the
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source to destination share. This operation can be disruptive.
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Response codes
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--------------
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.. rest_status_code:: success status.yaml
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- 202
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.. rest_status_code:: error status.yaml
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- 400
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- 401
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- 403
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- 404
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- 409
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Request
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-------
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.. rest_parameters:: parameters.yaml
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- project_id: project_id
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- share_id: share_id
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Request example
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---------------
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.. literalinclude:: samples/share-migration-complete-request.json
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:language: javascript
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Migration Get Process
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=====================
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.. rest_method:: POST /v2/{project_id}/shares/{share_id}/action
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.. versionadded:: 2.22
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Response codes
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--------------
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.. rest_status_code:: success status.yaml
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- 202
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.. rest_status_code:: error status.yaml
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- 400
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- 401
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- 403
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- 404
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- 409
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Request
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-------
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.. rest_parameters:: parameters.yaml
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- share_id: share_id
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- project_id: project_id
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Response parameters
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-------------------
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.. rest_parameters:: parameters.yaml
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- total_progress: total_progress
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- task_state: task_state
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Request example
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---------------
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.. literalinclude:: samples/share-migration-get-process-request.json
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:language: javascript
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Response_parameters
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-------------------
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.. literalinclude:: samples/share-migration-get-process-response.json
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:language: javascript
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Cancel Migration
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================
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.. rest_method:: POST /v2/{project_id}/shares/{share_id}/action
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.. versionadded:: 2.22
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Response codes
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--------------
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.. rest_status_code:: success status.yaml
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- 202
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.. rest_status_code:: error status.yaml
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- 400
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- 401
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- 403
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- 404
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- 409
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Request
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-------
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.. rest_parameters:: parameters.yaml
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- share_id: share_id
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- project_id: project_id
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Request example
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---------------
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.. literalinclude:: samples/share-migration-cancel-request.json
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:language: javascript
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