In cinder backup-create, whenever an attempt to do an incremental backup fails, it goes to doing a full backup. However, in this case, if the person had set the --incremental flag and then the incremental backup failed, then also the is_incremental flag never gets updated. Secondly, as of now, if there is an existing full backup for a volume, the next attempt for a backup create is always an incremental backup. However, cinder never actually updates the is_incremental flag unless the user had set it in the CLI command. An example is: [csaikia@localhost ~]$ cinder backup-create f24bae67-9342-42de-b01b-b63c55c84239 +-----------+--------------------------------------+ | Property | Value | +-----------+--------------------------------------+ | id | 59c17b88-a2c8-4d4d-b16c-c0a5a8312100 | | name | None | | volume_id | f24bae67-9342-42de-b01b-b63c55c84239 | +-----------+--------------------------------------+ [csaikia@localhost ~]$ cinder backup-show 59c17b88-a2c8-4d4d-b16c-c0a5a8312100 +-----------------------+--------------------------------------+ | Property | Value | +-----------------------+--------------------------------------+ | availability_zone | nova | | container | backups | | created_at | 2017-07-10T14:50:41.000000 | | data_timestamp | 2017-07-10T14:50:41.000000 | | description | None | | fail_reason | None | | has_dependent_backups | False | | id | 59c17b88-a2c8-4d4d-b16c-c0a5a8312100 | | is_incremental | False | | name | None | | object_count | 0 | | size | 1 | | snapshot_id | None | | status | available | | updated_at | 2017-07-10T14:50:45.000000 | | volume_id | f24bae67-9342-42de-b01b-b63c55c84239 | +-----------------------+--------------------------------------+ However from the logs, one can see that an incremental backup was performed: 10685 Jul 10 10:50:42 localhost.localdomain cinder-backup[11683]: DEBUG cinder.backup.drivers.ceph [None req-fedf4549-fda2-4745-add f-2c1e1c7a8da7 admin None] Volume file is RBD: attempting incremental backup. {{(pid=11683) backup /opt/stack/cinder/cinder/b ackup/drivers/ceph.py:894}} 10686 Jul 10 10:50:42 localhost.localdomain cinder-backup[11683]: DEBUG cinder.backup.drivers.ceph [None req-fedf4549-fda2-4745-add f-2c1e1c7a8da7 admin None] Using --from-snap 'backup.6990dcb4-2161-4979-a937-30c87f717a41.snap.1499698148.33' for incremental backup of volume f24bae67-9342-42de-b01b-b63c55c84239. {{(pid=11683) _backup_rbd /opt/stack/cinder/cinder/backup/drivers/cep h.py:636}} 10687 Jul 10 10:50:42 localhost.localdomain cinder-backup[11683]: DEBUG cinder.backup.drivers.ceph [None req-fedf4549-fda2-4745-add f-2c1e1c7a8da7 admin None] Creating backup snapshot='backup.59c17b88-a2c8-4d4d-b16c-c0a5a8312100.snap.1499698242.24' {{(pid=1 1683) _backup_rbd /opt/stack/cinder/cinder/backup/drivers/ceph.py:675}} 10688 Jul 10 10:50:43 localhost.localdomain cinder-backup[11683]: DEBUG cinder.backup.drivers.ceph [None req-fedf4549-fda2-4745-add f-2c1e1c7a8da7 admin None] Performing differential transfer from 'volume-f24bae67-9342-42de-b01b-b63c55c84239' to 'volume-f24 bae67-9342-42de-b01b-b63c55c84239.backup.base' {{(pid=11683) _rbd_diff_transfer /opt/stack/cinder/cinder/backup/drivers/ceph. py:562}} 10689 Jul 10 10:50:43 localhost.localdomain cinder-backup[11683]: DEBUG cinder.backup.drivers.ceph [None req-fedf4549-fda2-4745-add f-2c1e1c7a8da7 admin None] Piping cmd1='rbd export-diff --id cinder --conf /tmp/brickrbd_ST0vJ3 --pool volumes --from-snap ba ckup.6990dcb4-2161-4979-a937-30c87f717a41.snap.1499698148.33