RDM REPLICATION ON DELL COMPELLENT SRA

Hello we are using DELL COMPELLENT ENTERPRISE MANAGER  SRA to perform failover of our virtual machines on vmware. We have issue with one hard disk which is physical RDM lun. We replicated it but still we could not configure recovery of the vm on this disk. When we contacted vmware, they said the virtual disk and physical RDM must me in same consistency group. I don't understand what it means. Can some one help me