Hello,
Do you mean to set some sort of setting that will inform you when to overwrite the media? Have you created media sets, if yes, what is the Overwrite protection period and append period set for it?
In the Grandfather scenario, four media are used Monday through Thursday for
incremental or differential backups; another three media are used every Friday for full
backups. The remaining 12 media are used for monthly full backups and are kept off site.
The Grandfather strategy is recommended because it offers a goods media number to storage life ratio (19 media / 1 year).
It is also easy to modify if you want to incorporate more media. For example you could perform a full backup on the last Saturday of the month to archive permanently..
Additonally refer to:
http://support.veritas.com/docs/192265
http://support.veritas.com/docs/237374
In c ase you need any other info on this case, do write us back.