I have two VMware clusters 4.1 and 5.1 running in data centre A. Data centre B is running VMware 6 and is independent of the VMware instance in data centre A. There is a high speed connection between the two data centres and the LAN is extended. I need to move some VM's from A to B. I was going to use a tool called double take for the high priority machines to minimize down time but for the lower priority machines that could be powered off and migrated over night what are the other options. I won't be doing the migration but my managed service provider is advising I need to use double take for everything which is very costly. Thanks.