I am wondering what you guys do when it comes to making RMAN (11.2) long-term archival backups.

Following are the 3 options of making RMAN long-term archival backups. Need your advise (or practical experience) on a better one among the 3:

Making a monthly archival backup of a database via TSM TDPO to Data Domain. Currently, we use user-managed database backup (cold) via TSM. Every month-end, the monthly backup will occur and be migrated from Data Domain to TAPE.

Option 1: Take an OFFLINE RMAN backup:
backup database keep until time 'sysdate+30' restore point month-end.

Option 2: Take an ONLINE RMAN backup:
backup database keep unitl time 'sysdate+30' restore point month-end.
(this will include all archive logs till before the restore point)

Questions regarding above option 1 & 2 are:
Must I issue: change backup .... unavailable -- so that RMAN will NOT attempt to use this monthly archival backup during restore/recovery process?

How do you guys do to migrate an RMAN backup from Data Domain to TAPE?

Option 3: Let routine Level 0 RMAN backup run and exempt it from the current retention policy via: change backup .... keep until time 'sysdate+30'.

Do you think this option 3 is a better way of making archival backup?