Whenever you are trying to backup Archivelogs from RMAN you might get the following error.
Starting backup at 25-FEB-10
current log archived
archived log /u2/archivelogs/1_12241_642439782.dbf not found or out of sync with catalog
trying alternate file for archivelog thread 1, sequence 12241
released channel: ch1
RMAN-00569: =============== ERROR MESSAGE STACK FOLLOWS ===============
RMAN-03002: failure of backup command at 02/25/2010 10:05:30
RMAN-06059: expected archived log not found, lost of archived log compromises recoverability
ORA-19625: error identifying file /backup_restor_only/1_12241_642439782.dbf
ORA-27037: unable to obtain file status
SVR4 Error: 2: No such file or directory
Additional information: 3
If the archivelogs are no longer physically available, then you can issue the RMAN command “crosscheck copy of archivelog all”. This command checks for the physical existence of the archivelog file and will change the V$ARCHIVED_LOG.STATUS of the affected archivelog from “A” for AVAILABLE to “X” for EXPIRED. Once the archivelog file has a status of X, RMAN will no longer attempt to backup this archivelog file.
RMAN> crosscheck copy of archivelog all;
IMPORTANT NOTE: If there is no RMAN backup of the missing archivelog file, it is essential to perform a full-database backup. Otherwise, you may not be able to recover the database beyond missing log sequence number.