Update Share Migration Ocata Improvements Spec
New required changes have been discovered in coding phase. This change updates the spec accordingly. Change-Id: If02180ec3b5ae05c9ff18c9f5a054c33f13edcdf Partially-implements: blueprint ocata-migration-improvements
This commit is contained in:
Rodrigo Barbieri
parent
3c811aeb03
commit
e718599a43
@ -5,7 +5,7 @@
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http://creativecommons.org/licenses/by/3.0/legalcode
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==================================
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Share Migration Ocata Improvements
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Share migration Ocata improvements
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==================================
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https://blueprints.launchpad.net/manila/+spec/ocata-migration-improvements
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@ -21,19 +21,20 @@ feature `[1]`_. There were a few improvements suggested:
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* For driver-assisted migration, drivers may be able to migrate a share and its
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snapshots, but the API layer is blocking the request when there are
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snapshots.
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snapshots. This should only be the case when "force-host-assisted-migration"
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parameter is used.
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* There has been a lot of debate on whether the default value of non-disruptive
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parameter should be True or False. Currently it is also inconsistent with all
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other driver-assisted related parameters, defaulting to False while all the
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other driver-assisted parameters default to True.
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* There has been a lot of debate on whether the default value of
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"nondisruptive" parameter should be True or False. Currently it is also
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inconsistent with all other driver-assisted related parameters, defaulting to
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False while all the other driver-assisted parameters default to True.
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* The driver-assisted migration API parameters could be greyed out in the
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manila-ui "Start Migration" form so users better understand that "Force
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Host-assisted migration" negates the effects of the others.
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* Currently the API does not immediately return an error on the obvious
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incorrect combination of "Force host-assisted migration" and other
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incorrect combination of "force-host-assisted-migration" and other
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driver-assisted parameters set to True. This will be useful for when the
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manila-ui is not used.
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@ -64,33 +65,48 @@ Proposed change
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This spec proposes:
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1) Removing the snapshot restriction from the API layer, change it to work just
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like the other parameters' validation (writable, preserve_metadata, etc),
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thus adding an additional entry for migration_check_compatibility driver
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interface. Add the parameter to the API layer, named "preserve_snapshots".
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Also, this parameter, as the other ones, is not applicable for the
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host-assisted migration, preventing it from running if enabled.
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#) Removing the snapshot restriction from the API layer when
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"force-host-assisted-migration" is False, changing it to work just like the
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other parameters' validation (writable, preserve_metadata, etc), thus adding
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an additional entry for migration_check_compatibility driver interface. Add
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the parameter to the API layer, named "preserve_snapshots". Also, this
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parameter, as the other ones, is not applicable for the host-assisted
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migration, preventing it from running if enabled.
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2) Changing all REST API parameters to be mandatory, except for "force
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host-assisted migration". The purpose is to have better REST API support in
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the future, defaulting non-existing new REST API parameters to false when
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older microversions are used, and to avoid data loss in cases where the
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administrator does not specify a parameter by accident. For more
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#) Changing all REST API parameters to be mandatory, except for
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"force-host-assisted-migration". The purpose is to have better REST API
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support in the future, defaulting non-existing new REST API parameters to
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False when older microversions are used, and to avoid data loss in cases
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where the administrator does not specify a parameter by accident. For more
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information, see reference `[2]`_.
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3) Grey out the driver-assisted options in manila-ui when "Force host-assisted
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migration" is selected.
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4) Return an error when "Force host-assisted migration" API parameter is set
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#) Return an error when "force-host-assisted-migration" API parameter is set
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along with other driver-assisted migration API parameters.
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5) Improve the driver-assisted API parameters' descriptions in manila-ui and
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#) Improve the driver-assisted API parameters' descriptions in manila-ui and
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python-manilaclient to include "Enforce ..." in the name. Example: "Enforce
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Writable". Please note that this will not change the parameter name.
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6) Changing the validation that rejects the API request when the parameters are
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the same as the source share to do so only when the combination of "new
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share network", "new share type" and "destination pool" are the same.
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#) Changing the validation that rejects the API request when the parameters are
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the same as the source share. The correct behavior should be to return
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HTTP 200 "SUCCESS" if the parameters requested match the share's properties,
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already having the same "share network", "share type" and "pool".
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#) Migration should not be allowed to start when "access_rules_status" is in
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"ERROR" state. This is cause any migration to fail and should be blocked at
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the API layer. This spec proposes adding a validation for this.
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#) Export locations should not be shown for the destination share instance
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during a migration, due to the fact that this instance cannot be
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mounted (because new access rules cannot be added during a migration) thus
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confusing the user that can see two export locations while being unable to
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determine which one is mountable.
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#) With the addition of optional extra_specs saved in the Share model such as
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mount_snapshot_support, revert_to_snapshot_support and
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create_share_from_snapshot_support, it created the need to update these
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properties after a migration to match the destination instance share_type if
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it has been changed.
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Alternatives
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------------
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@ -114,11 +130,13 @@ None
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REST API impact
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---------------
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* The microversion will be bumped to include the changes proposed.
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* The microversion will be bumped to include the changes proposed. Support to
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previous microversion of migration-start will be dropped as we will only
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support the one with mandatory parameters.
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* The changes proposed will update the migration_start API as follows:
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- (POST, 202, 400, 409) migration-start: migrates share
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- (POST, 200, 202, 400, 409) migration-start: migrates share
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URL: /shares/<share_id>/action
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Body::
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@ -142,15 +160,21 @@ REST API impact
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* Not specifying any value for "nondisruptive", "preserve_snapshots",
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"writable" or "preserve_metadata" will now return error 400.
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* The same pool API restriction will be changed to not allow the same
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combination of "destination host", "share network" and "share type" as the
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source share.
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* The same pool API restriction will be changed to return 200 when the
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combination of "destination host", "share network" and "share type" is the
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same as the source share.
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* Specifying "force_host_assisted_migration" as True, along with any of
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"writable", "preserve_metadata", "preserve_snapshots" or "nondisruptive"
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being True, will also result in error 400, as it would be an incompatible
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combination.
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* Attempting a migration while "access_rules_status" is in "ERROR" will return
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error 400.
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* Export locations for the destination migration instance are no longer shown
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until migration is complete.
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Security impact
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---------------
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@ -166,15 +190,15 @@ Other end user impact
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This proposal will require updates to python-manilaclient. See example::
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manila migration-start <share> <host> <nondisruptive> <writable>
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<preserve_metadata> <preserve_snapshots> --force-host-assisted-migration
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--new-share-network --new-share-type
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manila migration-start <share> <host> --nondisruptive <True|False>
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--writable <True|False> --preserve-metadata <True|False>
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--preserve-snapshots <True|False> [--new-share-network <share_net>]
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[--new-share-type <share_type>]
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[--force-host-assisted-migration <True|False>]
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manila migration-start share_1 ubuntu@generic1#GENERIC1 True True True True
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manila migration-start share_1 ubuntu@generic1#GENERIC1 --writable True
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--nondisruptive False --preserve-metadata True --preserve-snapshots False
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Please note that during code implementation we may decide to change the syntax
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shown in the example above with regards to the mandatory driver-assisted
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parameters, in order to drive a better user experience with the CLI.
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As for manila-ui, there will be a new checkbox "Preserve Snapshots".
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@ -201,9 +225,213 @@ Driver maintainers will be prompted to update their driver-assisted migration
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parameter 'preserve_snapshots' introduced. In this change, it will be added to
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the existing implementations as "False".
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All existing migration driver interfaces will be updated to include
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snapshot-related parameters. See the new updated interfaces below::
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def migration_start(
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self, context, source_share, destination_share,
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source_snapshots, snapshot_mappings, share_server=None,
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destination_share_server=None):
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"""Starts migration of a given share to another host.
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.. note::
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Is called in source share's backend to start migration.
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Driver should implement this method if willing to perform migration
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in a driver-assisted way, useful for when source share's backend driver
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is compatible with destination backend driver. This method should
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start the migration procedure in the backend and end. Following steps
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should be done in 'migration_continue'.
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:param context: The 'context.RequestContext' object for the request.
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:param source_share: Reference to the original share model.
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:param destination_share: Reference to the share model to be used by
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migrated share.
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:param source_snapshots: List of snapshots owned by the source share.
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:param snapshot_mappings: Mapping of source snapshot IDs to
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destination snapshot models.
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:param share_server: Share server model or None.
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:param destination_share_server: Destination Share server model or
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None.
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"""
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raise NotImplementedError()
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def migration_continue(
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self, context, source_share, destination_share, source_snapshots,
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snapshot_mappings, share_server=None,
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destination_share_server=None):
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"""Continues migration of a given share to another host.
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.. note::
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Is called in source share's backend to continue migration.
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Driver should implement this method to continue monitor the migration
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progress in storage and perform following steps until 1st phase is
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completed.
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:param context: The 'context.RequestContext' object for the request.
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:param source_share: Reference to the original share model.
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:param destination_share: Reference to the share model to be used by
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migrated share.
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:param source_snapshots: List of snapshots owned by the source share.
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:param snapshot_mappings: Mapping of source snapshot IDs to
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destination snapshot models.
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:param share_server: Share server model or None.
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:param destination_share_server: Destination Share server model or
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None.
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:return: Boolean value to indicate if 1st phase is finished.
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"""
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raise NotImplementedError()
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def migration_complete(
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self, context, source_share, destination_share, source_snapshots,
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snapshot_mappings, share_server=None,
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destination_share_server=None):
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"""Completes migration of a given share to another host.
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.. note::
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Is called in source share's backend to complete migration.
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If driver is implementing 2-phase migration, this method should
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perform the disruptive tasks related to the 2nd phase of migration,
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thus completing it. Driver should also delete all original share data
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from source backend.
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:param context: The 'context.RequestContext' object for the request.
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:param source_share: Reference to the original share model.
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:param destination_share: Reference to the share model to be used by
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migrated share.
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:param source_snapshots: List of snapshots owned by the source share.
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:param snapshot_mappings: Mapping of source snapshot IDs to
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destination snapshot models.
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:param share_server: Share server model or None.
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:param destination_share_server: Destination Share server model or
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None.
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:return: If the migration changes the export locations or snapshot
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provider locations, this method should return a dictionary with
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the relevant info. In such case, a dictionary containing a list of
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export locations and a list of model updates for each snapshot
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indexed by their IDs.
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Example::
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{
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'export_locations':
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[
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{
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'path': '1.2.3.4:/foo',
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'metadata': {},
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'is_admin_only': False
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},
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{
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'path': '5.6.7.8:/foo',
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'metadata': {},
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'is_admin_only': True
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},
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],
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'snapshot_updates':
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{
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'bc4e3b28-0832-4168-b688-67fdc3e9d408':
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{
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'provider_location': '/snapshots/foo/bar_1'
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},
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'2e62b7ea-4e30-445f-bc05-fd523ca62941':
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{
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'provider_location': '/snapshots/foo/bar_2'
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},
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},
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}
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"""
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raise NotImplementedError()
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def migration_cancel(
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self, context, source_share, destination_share, source_snapshots,
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snapshot_mappings, share_server=None,
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destination_share_server=None):
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"""Cancels migration of a given share to another host.
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.. note::
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Is called in source share's backend to cancel migration.
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If possible, driver can implement a way to cancel an in-progress
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migration.
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:param context: The 'context.RequestContext' object for the request.
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:param source_share: Reference to the original share model.
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:param destination_share: Reference to the share model to be used by
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migrated share.
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:param source_snapshots: List of snapshots owned by the source share.
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:param snapshot_mappings: Mapping of source snapshot IDs to
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destination snapshot models.
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:param share_server: Share server model or None.
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:param destination_share_server: Destination Share server model or
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None.
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"""
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raise NotImplementedError()
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def migration_get_progress(
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self, context, source_share, destination_share, source_snapshots,
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snapshot_mappings, share_server=None,
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destination_share_server=None):
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"""Obtains progress of migration of a given share to another host.
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.. note::
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Is called in source share's backend to obtain migration progress.
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If possible, driver can implement a way to return migration progress
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information.
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:param context: The 'context.RequestContext' object for the request.
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:param source_share: Reference to the original share model.
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:param destination_share: Reference to the share model to be used by
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migrated share.
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:param source_snapshots: List of snapshots owned by the source share.
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:param snapshot_mappings: Mapping of source snapshot IDs to
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destination snapshot models.
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:param share_server: Share server model or None.
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:param destination_share_server: Destination Share server model or
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None.
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:return: A dictionary with at least 'total_progress' field containing
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the percentage value.
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"""
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raise NotImplementedError()
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As can be noted above, the migration_complete driver interfaces had its
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return value changed to return a dictionary structure containing the export
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locations and a dictionary of snapshot updates, containing model updates for
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each snapshot, in order to update the provider location in manila's database.
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Implementation
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==============
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When starting a driver-assisted migration, it will be checked if drivers can
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support "preserve_snapshots" regardless of the API option specified, due to the
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fact that the migrating share may have existing snapshots. In case the driver
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does not support "preserve_snapshots", an error message will be raised, stating
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that driver-assisted migration cannot proceed while the share has snapshots.
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If the driver does support "preserve_snapshots", it will be checked if all
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existing snapshots have 'available' status. If so, destination snapshot
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instances respective to each source snapshot instance will be created in the
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database. Finally, a list of source snapshot instances and a mapping
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dictionary, that comprises of destination snapshot instances indexed by source
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snapshot instance IDs, will be passed to drivers in the updated driver
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interfaces.
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This mapping and list of snapshots will be easily retrieved from the database
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at later stages such as when invoking migration_continue and
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migration_complete. After migration is complete, the snapshot instances will be
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updated according to the model updates returned by the driver, with fields such
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as "provider_location" and "export_locations".
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As for host-assisted migration, the validation of existing snapshots present in
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in the API layer, has been copied to before starting a host-assisted migration,
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as it will prevent the host-assisted migration from running.
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Finally, the optional extra_specs of the share model are updated according to
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the destination share type.
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Assignee(s)
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-----------
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Loading…
Reference in New Issue
Block a user