Backup levels

To provide flexibility, the ON-Bar and ontape utilities support three backup levels.

Level 0: Level 0 backs up all used pages that contain data for the specified storage spaces.
You need all these pages to restore the database to the state that it was in at the time that you made the backup.; Level-0 backups can be time-consuming because ON-Bar writes all the disk pages to back up media. Level-1 and level-2 backups might take almost as much time as a level-0 backup because the database server must scan all the data to determine what has changed since the last backup. It takes less time to restore data from level-0, level-1, and level-2 backups than from level-0 backups and a long series of logical-log backups.
Level 1: Level 1 backs up only data that has changed since the last level-0 backup of the specified storage spaces.
All changed table and index pages are backed up, including those pages with deleted data. The data that is copied to the backup reflects the state of the changed data at the time that the level-1 backup began.; A level-1 backup takes less space and might take less time than a level-0 backup because only data that changed since the last level-0 backup is copied to the storage manager.
Level 2: Level 2 backs up only data that has changed since the last level-1 backup of the specified storage spaces.
A level-2 backup contains a copy of every table and index page in a storage space that has changed since the last level-1 backup.; A level-2 backup takes less space and might take less time than a level-1 backup because only data that changed since the last level-1 backup is copied to the storage manager.

Important: If disks and other media are destroyed and need to be replaced, you need at least a level-0 backup of all storage spaces and relevant logical logs to restore data completely on the replacement hardware.