Hello,

We've got over 100 Oracle instances with Netbackup for Oracle agent installed.  We backup using RMAN scripts that are quite similar across all instances.

The thing is as observing Oracle backups, sometimes we encounter a nasty issue we don't know how to resolve.
Our RMAN script is quite straightforward:

(1)  ALLOCATE CHANNEL ch00 TYPE 'SBT_TAPE';
(2)  ALLOCATE CHANNEL ch01 TYPE 'SBT_TAPE';
       SEND 'NB_ORA_POLICY=<policy name>';
       BACKUP
       $BACKUP_TYPE
       DATABASE;
       sql 'alter system archive log current';
(3)  RELEASE CHANNEL ch00;
(4)  RELEASE CHANNEL ch01;
# backup all archive logs
(5) ALLOCATE CHANNEL ch00 TYPE 'SBT_TAPE';
(6) ALLOCATE CHANNEL ch01 TYPE 'SBT_TAPE';
      SEND 'NB_ORA_POLICY=<policy name>';
      BACKUP
      filesperset 20
      FORMAT 'al_%s_%p_%t'
      ARCHIVELOG ALL DELETE INPUT;
      RELEASE CHANNEL ch00;
      RELEASE CHANNEL ch01;

The issue described below sometimes happens to our DBs and regards to RMAN channel allocation/release.

The problem is that  one of the RMAN channels allocated at lines (1) or (2 ) occasionally fails during database backup. The channel failure actually doesn't stop backup, RMAN uses the remaining channel to backup the rest of Oracle data files. After data files backup successfully completes through the remaining channel, RMAN tries to release channel at lines (3) and (4) and eventually generates a error while trying to release the failed channel.
The most important point is that the error raised during releasing of failed channel is transfered by RMAN to NetBackup and the latter treats this error as the failure of entire database backup.

Unfortunately, NetBackup considers this issue as a backup error and invokes another attempt of databse backup. This NetBackup behaviour leads to excessive backups, the same data files are backed up twice.

The most obvious solution is to comment lines (3) and (4) to prevent explicit channel release and use other channel IDs at lines (5) and (6) to prevent errors caused by attempts to open an existing channel.

So my concern are have anyone expirienced the same problem with RMAN backup and what is the best solution under these circumstances?