Are you using the DSS iSCSI Failover feature and the latest version? Link below provides how to setup the DSS Failover feature.

http://www.open-e.com/library/product-presentations/

Library
Product Presentations

Open-E Replications

2008 - Open-E DSS Volume Replication with Failover over a LAN, February 2009

Open-E in Virtual Appliances

2009 - Multipath with Virtual Iron and Open-E Data Storage Server, December 2008