Backup to Disk, then duplicate/move to tape when expired
I'm hoping I'm missing something, but I haven't been able to find a way to do this.
The plan is to retain 3 months of backups on Disk, and any copies outside of that live on tape. In practice this means our "weekly" (1 month retention) and "monthly" (3 month retention) backups live on disk only, since they expire within that time. However, "quarterly" (1 year retention) and "yearly" (infinite retention) live on disk for 3 months, after which they only exist on tape.
I've been using SLPs, but it occurred to me that for the first 3 months, I end up with copies on disk as well as tape. This is unnecessary and unwanted, and the space on disk/tape does add up when one considers our whole environment.
Is there a way for a given backup to live on disk, then duplicate (if necessary) to tape once the disk copy expires?