I have an HP server with 4 146GB hard drives. I have set backup exec to backup my data once a week (full backup). However, the 1TB cartridge in my Dell RD1000 backup device will not hold all the data on the hard drives. Shouldn't a 1 TB cartridge hold at least the 500 GB the 4 hard drives hold? I'm at a loss here. Not all my data is being backed up.