
* If the user skips a BACKUP STAGE, then all intermediate backup stages will
automatically be run. This will allow us to add new stages within the BACKUP
STAGE hierarchy in the future with even more precise locks without causing
problems for tools using an earlier version of the BACKUP STAGE implementation.
* One can use the max_statement_time or lock_wait_timeout system variables to
ensure that a BACKUP STAGE command doesn't block the server too long.
* DDL logging will only be available in MariaDB Enterprise Server 10.2 and
later.
* A disconnect will automatically release backup stages.
* There is no easy way to see which is the current stage.

URL: https://mariadb.com/kb/en/backup-stage/