Please refer to the EMC E-Lab Interoperability Navigator(https://elabnavigator.emc.com/) for tested and supported array versions. Citrix is restricting support for ISL on XenServer 6.1 to VNX Block OE version 5.31 and later used with SMI-S Provider version 4.4.0.2 or 4.5. ISL requires EMC VNX licenses for SnapView and SANCopy.