Ok here is the process
We need one year of backups available
So at the end of the year we rotate old backups quarterly. So about 120 tapes every three months go back into the machihne and get overwriten.
We use Full backups for small jobs and only incrementals on brick mailbox level backups and the huge file server obviously. We don't use snapshot but we do use the GRT option even though it doesent work because we use tape backups so it's pretty much useless since it ocpies the entire database to the backup server (staging area) even when you choose one little message.