Extending/Adding Storage through tape cartirdge?

We are using Symantec Backup Exec 2012 installed on our file server and Eternus L20 S2 for our backups. This Eternus L20 S2 tape machine have 8 slot where we insert tapes as storage to put our backups. Recently our file server disk capacity are getting low. Is it possible that this tape cartridge be used to expand our file server capacity by adding the tapes storage to our disk storage? Hope you can provide us idea. Thank you.