The A/A means for your question with regards to your Taget 0 that both DSS V7 will have this iSCSI volume being replicated, so lets say DSS-A is the Source volume and DSS-B is the Destination volume, so when you read and write to your Target0 that it is first written to DSS-A and if there is a failover then DSS-B will be the Source until DSS-A is back online then it will update and you have to move back the resources to DSS-A if you want to place back to its origanal position and be source again and this only takes a few seconds. But all the time data is not inturupted.