There are situations when the backup information between RMAN catalog and Tivoli Storage Manager (TSM) is not in sync. Hence there are backup pieces found in TSM catalog which are not available in RMAN catalog or vice versa.
There is a need here to release the tapes for recycling by removing irrelevant or unwanted backup pieces from them as well as synchronize the RMAN catalog with TSM catalog.
When an RMAN delete command is run, RMAN deletes entries in the recovery catalog before confirmation from the Tivoli Storage Manager server. In cases where objects are not found on the Tivoli Storage Manager server, RMAN tries to delete backup sets from the Tivoli Storage Manager server and fails. However, the entries in the RMAN catalog for these objects are still removed. When this happens, RMAN can no longer identify these backups through the catalog even though the file still exists on the Tivoli Storage Manager (TSM) server. Hence the discrepancies appear between RMAN catalog and TSM catalog information.
IBM provides a utility called 'tdposync' which does this job efficiently.
How it WorksThe tdposync utility finds the backup pieces on the TSM that are not in the RMAN catalog. It provides the option to correct these discrepancies between the TSM and the RMAN catalog. Hence we can reclaim space on the TSM by deleting the irrelevant / unwanted backup pieces.
CautionIf there are backups in RMAN catalog marked as EXPIRED, RMAN still considers these backup pieces as existing. If tdposync is invoked against these backup pieces, it will identify these backup in the RMAN catalog and TSM and will not delete them from TSM as the information is found in sync. So, it is necssary to delete these backups from the RMAN catalog so that it can be deleted from the TSM. It is advisable to run RMAN CROSSCHECK command to validate whether the backups exist and then use RMAN 'DELETE EXPIRED' command to delete the information from the RMAN catalog.
'tdposync' in ActionAs explained in IBM manuals, here is how 'tdposync' works:
When you invoke tdposync, the utility does the following:
1. Prompts you for information
2. Gathers information for the Oracle server(s)
3. Queries the Oracle backup catalog and the Tivoli Storage Manager server
4. Displays formatted output to the screen (files that exist on Tivoli Storage Manager but not in the RMAN catalog)
5. Prompts you to do one of the following:
+ Delete any files found causing the discrepancy.
+ Delete all files.
+ Exit the program without deleting files from the Tivoli Storage Manager server.