Values:
STATE_UNSPECIFIED (0):
State not set.
CREATING (1):
Backup is being created. While in this state,
the snapshot for the backup point-in-time may
not have been created yet, and so the
point-in-time may not have been fixed.
UPLOADING (2):
Backup is being uploaded. While in this
state, none of the writes to the volume will be
included in the backup.
READY (3):
Backup is available for use.
DELETING (4):
Backup is being deleted.
ERROR (5):
Backup is not valid and cannot be used for
creating new volumes or restoring existing
volumes.
UPDATING (6):
Backup is being updated.
