Many thanks for the response.
Is there any doc for step by step procedure to perform Failover settings changes?
Yes, all ESX hosts (ESX 4.0, ESXi 4.1 and ESXi 5.0) in one group.
Because each ESX LUNs are presented to each ESX hosts (ESX 4.0, ESXi 4.1 and ESXi 5.0) that is the reason all ESX host are in one Group.
Kindly suggest me the best practices from EMC. Can I go for separate group for each flavor?
"Can I change failover settings online?"
ID: emc117938 Usage: 26 Date Created: 09/16/2005 Last Modified: 03/13/2012 STATUS: Approved Audience: Customer Knowledgebase Solution Question: Can I change failover settings online? Environment: Product: CLARiiON CX Series Environment: EMC SW: Access Logix Environment: OS: UNIX Environment: OS: Microsoft Windows Fix: No, you must change the settings when the host is offline (No I/O going to the array from the host). If you change failover mode online (during production), you will lose access to data. Furthermore, entering incorrect values could cause the storage system to be unmanageable or unreachable by the host, and could cause the failover software to operate incorrectly.
NOTE: You must reboot the host after making the changes.
So it looks like you actually have to bring the server down, change the failover mode and then bring it back up.
What array are you using ?
In Unisphere, go to Hosts ..you will see under Wizards "Failover Wizard".
Here is a good paper on VNX and vSphere integration