The VTL works with the Dynamic Unit to create Virtual Tapes. See link below for more info.

http://www.open-e.com/library/how-to-resources/

Open-E Backups
# 2010.09 Open-E Different Backups

# 2011.01 Open-E Backup to iSCSI Target Volume over a LAN

# 2010.10 Open-E Backup to a Dynamic Volume with USB drive