A copy of the Backup Database can be installed on any server machine in a cell. The Backup Database stores two types of records used to track all of the backups done in the cell:
· Dump set records, which list the fileset family and the tape used in each dump set
· Administrative records, which list the fileset families, dump levels, and tape hosts
Because information about dumps is difficult to re-create, it is important that you copy the Backup Database with the bak savedb command periodically, perhaps weekly. When you issue the bak savedb command, the entire database is copied to tape. One tape needs to be designated as a Backup Database tape; when the command is issued, the tape is labeled with the name bak_db_dump.1.
If the Backup Database becomes damaged (for instance, if the disk that houses the database becomes damaged), you must delete the old database and restore an entirely new version from its backup tape. You can use the bak verifydb command to determine if the Backup Database is damaged.
Do not attempt to recover information from a corrupted database. Instead, use the bos stop command to shut down all bakserver processes. Then remove the old Backup Database and its associated files from each machine on which it is located; the files for the Backup Database are named dcelocal/var/dfs/backup/bkdb.* on each machine on which the database resides.
Once the database is removed, use bos start to restart all bakserver processes on the machines where they were running. Use bak addhost to add a tape host for the Tape Coordinator from which you will restore the Backup Database, and use bak restoredb to restore the new version of the database. Re-create fileset information in the database as needed, restoring dump set information that you may have lost since the last backup of filesets; note that any fileset family, fileset family entry, or host information updated since the last backup of the Backup Database must be re-created as well.
If specific information about a dump set is accidentally deleted from the Backup Database, you can use the bak scantape command with the -dbadd option to check the backup tape used for the dump set, recover the dump set information, and add the information to the Backup Database. Do not use the bak scantape command to attempt to reconstruct the database.
More:
Backing Up the Backup Database
Recovering Specific Backup Data