Keeping the past 3 years archived data on Symantec EV by migrating the rest of closed partition to tape using Netbackup ?

People,

I'm planning to reduce the disk space usage of the EV 9.0.4 LUN by sending all of the data older than 3 years off to tape by using Symantec Netbackup v7.6.

How can I achieve this while still allowing user to retrieve the archived email & file when they double click on the Outlook archived email and also the file server place holder ?

Once I migrate the existing EV 9 to EV 10, can user still receive those archived item written to tape after the EV 9 server & SQL 2005 database has been decommisioned ?