The cinder.interface.volume_group_driver Module

The cinder.interface.volume_group_driver Module

Generic volume group volume driver interface.

class VolumeGroupDriver

Bases: cinder.interface.base.CinderInterface

Interface for drivers that support groups.

create_group(context, group)

Creates a group.

Parameters:
  • context – the context of the caller.
  • group – the Group object to be created.
Returns:

model_update

model_update will be in this format: {‘status’: xxx, ……}.

If the status in model_update is ‘error’, the manager will throw an exception and it will be caught in the try-except block in the manager. If the driver throws an exception, the manager will also catch it in the try-except block. The group status in the db will be changed to ‘error’.

For a successful operation, the driver can either build the model_update and return it or return None. The group status will be set to ‘available’.

create_group_from_src(context, group, volumes, group_snapshot=None, snapshots=None, source_group=None, source_vols=None)

Creates a group from source.

Parameters:
  • context – the context of the caller.
  • group – the Group object to be created.
  • volumes – a list of Volume objects in the group.
  • group_snapshot – the GroupSnapshot object as source.
  • snapshots – a list of Snapshot objects in the group_snapshot.
  • source_group – a Group object as source.
  • source_vols – a list of Volume objects in the source_group.
Returns:

model_update, volumes_model_update

The source can be group_snapshot or a source group.

param volumes is a list of objects retrieved from the db. It cannot be assigned to volumes_model_update. volumes_model_update is a list of dictionaries. It has to be built by the driver. An entry will be in this format: {‘id’: xxx, ‘status’: xxx, ……}. model_update will be in this format: {‘status’: xxx, ……}.

To be consistent with other volume operations, the manager will assume the operation is successful if no exception is thrown by the driver. For a successful operation, the driver can either build the model_update and volumes_model_update and return them or return None, None.

create_group_snapshot(context, group_snapshot, snapshots)

Creates a group_snapshot.

Parameters:
  • context – the context of the caller.
  • group_snapshot – the GroupSnapshot object to be created.
  • snapshots – a list of Snapshot objects in the group_snapshot.
Returns:

model_update, snapshots_model_update

param snapshots is a list of Snapshot objects. It cannot be assigned to snapshots_model_update. snapshots_model_update is a list of dictionaries. It has to be built by the driver. An entry will be in this format: {‘id’: xxx, ‘status’: xxx, ……}. model_update will be in this format: {‘status’: xxx, ……}.

The driver should populate snapshots_model_update and model_update and return them.

The manager will check snapshots_model_update and update db accordingly for each snapshot. If the driver successfully deleted some snapshots but failed to delete others, it should set statuses of the snapshots accordingly so that the manager can update db correctly.

If the status in any entry of snapshots_model_update is ‘error’, the status in model_update will be set to the same if it is not already ‘error’.

If the status in model_update is ‘error’, the manager will raise an exception and the status of group_snapshot will be set to ‘error’ in the db. If snapshots_model_update is not returned by the driver, the manager will set the status of every snapshot to ‘error’ in the except block.

If the driver raises an exception during the operation, it will be caught by the try-except block in the manager and the statuses of group_snapshot and all snapshots will be set to ‘error’.

For a successful operation, the driver can either build the model_update and snapshots_model_update and return them or return None, None. The statuses of group_snapshot and all snapshots will be set to ‘available’ at the end of the manager function.

delete_group(context, group, volumes)

Deletes a group.

Parameters:
  • context – the context of the caller.
  • group – the Group object to be deleted.
  • volumes – a list of Volume objects in the group.
Returns:

model_update, volumes_model_update

param volumes is a list of objects retrieved from the db. It cannot be assigned to volumes_model_update. volumes_model_update is a list of dictionaries. It has to be built by the driver. An entry will be in this format: {‘id’: xxx, ‘status’: xxx, ……}. model_update will be in this format: {‘status’: xxx, ……}.

The driver should populate volumes_model_update and model_update and return them.

The manager will check volumes_model_update and update db accordingly for each volume. If the driver successfully deleted some volumes but failed to delete others, it should set statuses of the volumes accordingly so that the manager can update db correctly.

If the status in any entry of volumes_model_update is ‘error_deleting’ or ‘error’, the status in model_update will be set to the same if it is not already ‘error_deleting’ or ‘error’.

If the status in model_update is ‘error_deleting’ or ‘error’, the manager will raise an exception and the status of the group will be set to ‘error’ in the db. If volumes_model_update is not returned by the driver, the manager will set the status of every volume in the group to ‘error’ in the except block.

If the driver raises an exception during the operation, it will be caught by the try-except block in the manager. The statuses of the group and all volumes in it will be set to ‘error’.

For a successful operation, the driver can either build the model_update and volumes_model_update and return them or return None, None. The statuses of the group and all volumes will be set to ‘deleted’ after the manager deletes them from db.

delete_group_snapshot(context, group_snapshot, snapshots)

Deletes a group_snapshot.

Parameters:
  • context – the context of the caller.
  • group_snapshot – the GroupSnapshot object to be deleted.
  • snapshots – a list of Snapshot objects in the group_snapshot.
Returns:

model_update, snapshots_model_update

param snapshots is a list of objects. It cannot be assigned to snapshots_model_update. snapshots_model_update is a list of of dictionaries. It has to be built by the driver. An entry will be in this format: {‘id’: xxx, ‘status’: xxx, ……}. model_update will be in this format: {‘status’: xxx, ……}.

The driver should populate snapshots_model_update and model_update and return them.

The manager will check snapshots_model_update and update db accordingly for each snapshot. If the driver successfully deleted some snapshots but failed to delete others, it should set statuses of the snapshots accordingly so that the manager can update db correctly.

If the status in any entry of snapshots_model_update is ‘error_deleting’ or ‘error’, the status in model_update will be set to the same if it is not already ‘error_deleting’ or ‘error’.

If the status in model_update is ‘error_deleting’ or ‘error’, the manager will raise an exception and the status of group_snapshot will be set to ‘error’ in the db. If snapshots_model_update is not returned by the driver, the manager will set the status of every snapshot to ‘error’ in the except block.

If the driver raises an exception during the operation, it will be caught by the try-except block in the manager and the statuses of group_snapshot and all snapshots will be set to ‘error’.

For a successful operation, the driver can either build the model_update and snapshots_model_update and return them or return None, None. The statuses of group_snapshot and all snapshots will be set to ‘deleted’ after the manager deletes them from db.

update_group(context, group, add_volumes=None, remove_volumes=None)

Updates a group.

Parameters:
  • context – the context of the caller.
  • group – the Group object to be updated.
  • add_volumes – a list of Volume objects to be added.
  • remove_volumes – a list of Volume objects to be removed.
Returns:

model_update, add_volumes_update, remove_volumes_update

model_update is a dictionary that the driver wants the manager to update upon a successful return. If None is returned, the manager will set the status to ‘available’.

add_volumes_update and remove_volumes_update are lists of dictionaries that the driver wants the manager to update upon a successful return. Note that each entry requires a {‘id’: xxx} so that the correct volume entry can be updated. If None is returned, the volume will remain its original status. Also note that you cannot directly assign add_volumes to add_volumes_update as add_volumes is a list of volume objects and cannot be used for db update directly. Same with remove_volumes.

If the driver throws an exception, the status of the group as well as those of the volumes to be added/removed will be set to ‘error’.

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