Creating Grandfather-Father-Son Backup Scheme in Backup Exec 15
I would suggest that you avoid partitioning your library unless you have a very good reason. If you have partitions and do not set your OPP and AP correctly, your jobs will run out of tapes in the targeted partition and will probably fail. BE will not use tapes in other partitions even if they are available.
Set up the appropriate number of media sets with the correct OPP and AP. This should be sufficient for your purpose. In the event that you did not set up your OPP correctly and there is insufficient tapes in the targeted media set, BE can use tapes from other media set.
Read this document for a better understanding of OPP and AP.
http://www.veritas.com/docs/000032654
After setting up your media sets, do not associate them with the new media set. Otherwise, they would use the OPP of the media set and would be write protection immediately. Leave all your tapes in the scratch media set. Your jobs will use the tapes from the scratch media set and move them to the targeted media set after the job is completed.
You should also read the section in the Admin Guide on tape management.
Also, when moving from tape drives to tape library, you should also change your mindset that the backups for a particular day must end up on a particular tape. You should allow BE to use whichever tape it wants. It will manage the tapes for you. Don't waste time micro-managing your tapes. See my article below
https://www.veritas.com/community/articles/must-mondays-backup-be-monday-tape
As an aside, if you are not using barcode labels, you should do so. They make for more efficient tape library operation. See my article below
https://www.veritas.com/community/articles/using-barcode-labels-why-and-how