TIP #46 : Using 'Plus archivelog' in backup

I had a client which using Oracle 10gR3 on Windows.Its backup strategy was simple. Daily incremental level 1 backup and weekly level 0 backup.Database was configured to use flash recovery area for archivelogs and backups.
I regularly get flash recovery full problem with retention policy 2 weeks.Suprisingly database is only 1GB.
Bacjup script was as simple as 'backup database ...... plus archivelog ';

Finally, I found that problem was because of plus archivelog.
Regarding to RMAN document, RMAN performs these steps when "plus archivelog" command is in backup script.

1. Runs an ALTER SYSTEM ARCHIVE LOG CURRENT statement.
2. Runs the BACKUP ARCHIVELOG ALL command. Note that if backupoptimization is enabled, then RMAN only backs up logs that have not yetbeen backed up.
3. Backs up the files specified in the BACKUP command.
4. Runs an ALTER SYSTEM ARCHIVE LOG CURRENT statement.
5. Backs up any remaining archived redo logs.

If backup otimization is off (default RMAN), each time all archivelogs are backed up which means that on daily basis backup size grows since archivelogs in flash recovery are not removed as space exists.

In a nutshell, when "plus archivelog" is used in backup script , make sure that optimization is on in RMAN configuration otherwise in each backup whole archive logs are backed up.