Figure 18 describes the ON–Bar warm-restore sequence.
In a warm restore, the onbar-driver sends a list of backup objects to the Backup Scheduler. The Backup Scheduler creates a restore session that contains lists of backup objects to restore and might start one or more onbar-worker processes. The onbar-worker transfers data between the storage manager and the database server until the warm restore is complete. 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). Next, ON–Bar backs up the logical logs to get the latest checkpoint and then restores them. This logical-log backup allows data to be restored as close to the moment of failure as possible.
As each object is restored, information about the restore is added to the sysutils database. As each logical log is backed up, information about it is added to sysutils and the emergency boot file. The emergency backup boot file is on the coserver of the onbar-worker that backed it up.