You should take a look on disk staging.

It seems to solve the task you describe du describe.
And it will even try to keep your disk staging unit full at all time and 
only remove the images when it needs diskspace.
Duplication to tape is done automaticly

I have implemented this and it ruuns without any problem. I use NBU 5.1 MP2 
on with Windows 2003 for the master and media servers.

You could also do this with vault and a normal disk unit.

/johnny


At 15:50 10-05-2005 -0700, Jeffrey Dykzeul wrote:
>I am hoping somebody is already doing something similar to what I describe
>below and can direct me to the appropriate techniques/commands using
>NetBackup.
>
>1) I want to try staging backups to disk on my master/media server.
>2) Once backups to disk are complete, I want to duplicate some selection of
>the images
>      to tape for offsite storage.
>3) Once the tapes are made for offsite storage, I want to leave the images
>on disk for a
>      limited amount of time, perhaps a week, then remove them to free up
>disk space. But
>      I still want to be able to recover from the offsite tapes within a
>reasonable period of time,
>      say 6 months, without having to import the images to determine what is
>on the tapes.
>
>I have a pretty good idea of how to do 1 (create/use disk storage units) &
>2 (bpduplicate), but if you know of any gotchas or nifty techniques, I'm
>happy to listen. I'm not clear on how to accomplish step 3.
>
>
>Jeff Dykzeul
>Raytheon Space & Airborne Systems
>
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