Figure 16 describes the ON–Bar warm-restore sequence.
In a warm restore, the onbar-driver creates a list of restore objects. In a parallel restore (if BAR_MAX_BACKUP is not set to 1), the ON–Bar driver starts onbar_d child processes. The onbar_d processes transfer data between the storage manager and the database server until the warm restore is complete. Each onbar_d process processes one storage space. In a serial restore, the onbar-driver restores the storage spaces one at a time. Then the onbar-driver performs the logical backup and restore. After each object is restored, information about it is added to the sysutils database.
For each storage space, ON–Bar restores the last level-0 backup, the level-1 backup (if it exists), and the level-2 backup (if it exists). After the physical restore is complete, ON–Bar backs up the logical logs to get the latest checkpoint and then restores the logical logs. This logical backup allows data to be restored up to the moment of failure.