Oracle 11g: RMAN catalog resynchronization

To synchronize the target database control file with the catalog :

RAM> RESYNC CATALOG;

To check if backups on file system are deleted but still referenced in the rman catalog:
    a) for backupset

RMAN> crosscheck backupset;
allocated channel: ORA_DISK_1
channel ORA_DISK_1: SID=143 device type=DISK
using channel ORA_SBT_TAPE_1
crosschecked backup piece: found to be 'EXPIRED'
backup piece handle=43mraiho_1_1 RECID=59 STAMP=766855736
crosschecked backup piece: found to be 'EXPIRED'
backup piece handle=44mrail9_1_1 RECID=60 STAMP=766855849
crosschecked backup piece: found to be 'EXPIRED'
backup piece handle=4cmraj7q_1_1 RECID=62 STAMP=766856442
crosschecked backup piece: found to be 'EXPIRED'
backup piece handle=4dmral4o_1_1 RECID=63 STAMP=766858392
crosschecked backup piece: found to be 'EXPIRED'
backup piece handle=4lmranr6_1_1 RECID=65 STAMP=766861158
crosschecked backup piece: found to be 'EXPIRED'
backup piece handle=4mmranun_1_1 RECID=66 STAMP=766861271
crosschecked backup piece: found to be 'EXPIRED'
backup piece handle=4nmrao37_1_1 RECID=67 STAMP=766861415
Crosschecked 7 objects

For a specific device type

RMAN> crosscheck backupset device type sbt;

    b) for image copy

RMAN> crosscheck copy;

The crosscheck check if the backup still exists on file system; if not the backuppiece is marked as EXPIRED.

To list expired backupset :

RMAN> list expired backupset;
RMAN> list expired backupset summary;

To list expired copy :

RMAN> list expired copy;

To delete expired backupset or copy:

RMAN> delete expired backupset;
RMAN> delete expired copy;

It is also possible to check for obsolete backup. An obsolete backup is a backup that is not used to garantee the retention policy.
To check for obsolete backup :

RMAN> report obsolete;

To delete obsolete backup :

RMAN> delete obsolete;