Currently DSS Volume Replication for iSCSI Targets is manual failover.
Typical setup would involve the following:

1 - DSS set as Source - located in Volume Replication
Logical Volumes to be set the same size
1 - DSS set as Destination - located in Volume Replication
Logical Volumes to be set the same size

If Source failed logically or physically set Destination to Source. Then set failed Source to Destination.

Then enable the Target in Target Manager and access the initiator to logon the Target IP address of the new Source.

You can download and test with DSS for a full 30 day trail version by accessing link below additionally the manual and online help to assist.

http://www.open-e.com/data_storage_s...l_cd_downloads