Hi,  I'll just update this as I've resolved the problem now. It turns out that my issue was because if a LUN is presented directly to a Windows host as opposed to via vSphere, the destination LUN can't be accessed on the original host.  You need to give a different Windows host access to it. Of course, when you failover back again, the original host gets the LUN back.  It was disappointing that I had to resolve this myself and EMC support were no help but perhaps this might help others getting the replication working. Now the next step is to get it working when presented through vSphere.  Cheers, Paul.
Good Afternoon,  I'm after some advice on what I'm probably doing wrong with regards to getting LUN replication and failover not working as expected using Windows 2008 R2. I have two VNXe3200's that are configured for LUN replication. VNXe2 is the source and VNXe1 is the destination.  The replication looks like it is working fine from the VNXe side. We have one host called MPIO that has initiators configured to both VNXe's but it only has access to the LUN on VNXe2 currently.  The issue I am getting is that i don't know how Windows should act when the LUN is failed over to VNXe1. Should the LUN still be accessible and the pathing be handled by the only connection it has to VNXe2 or will I have to allow access to the replicated LUN on VNXe1 that is now the source?  If i do that though, the server see's the LUN as a new disk and wants to initialize and format it. That will of course lose all the data.   I've has EMC support looking at this but have been told it's a Windows issue, not a VNXe one. I'm in limbo at the moment with this and I don;t disagree with them but I can't find any information on exactly how this replication should work from a server side (apart from getting MPIO and iSCSI seeing only one drive which i have done).  Sorry if this isn't too clear and i can take screenshots etc... if required.  Thanks, Paul.
Two VNXe3200's with iSCSI LUN replication and failover not working.