Thank you for getting back to me so fast. I have Boot lun's to be in different storage group and datastores in different storage groups. But i have 1 ESXi server with 2 HBA's. So is there a wway to get around this ????

Yes for example i have VDR as esx host. I have 2 storage groups VDR_boot and VDR_datastores. Boot lun's sits in the Boot storage group and the Data store lun's sits in the VDR_datastores storage group. But i have 2 HBA's for the VDR host. How can i assign the same host to 2 different storage groups ?

you create individual storage groups for each host, the first LUN you add to each SG is the boot LUN. Then when you provision regular LUNs for datastore ..you simply add them to each individual storage group. Do make sure that Host ID (column on the far right) for each LUN that you are adding is identical for each host.

you can't, you will need to collapse both storage groups into one.

no, but you can add LUNs to multiple storage groups

you have Cisco USC ? Take a look at this article

http://virtualeverything.wordpress.com/2011/05/31/simplifying-san-management-for-vmware-boot-from-san-utilizing-cisco-ucs-and-palo/

if you can create vHBAs then you can dedicate two for the boot LUN and two for the data LUNs.

In this case you need to go into "engineering mode" in order to segregate your "Boot initiator" and your "Datastore initiator" because ESX will be automatically registered with ALL the vHBA into Unisphere.

or disable autregistration in ESX and manually register

http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=1027029

I manually registered the ESX on the VNX side.... so the solution is to have 4 hbs's to solve this ? oras Julen said is there a run around in the engg mode ????

he is referring to the fact that when you zone an ESX hosts to VNX, if there are 4 HBAs, all 4 will register as one "host". You need to manually register them so that 2 HBAs are treated  as one host and connect to storage group with the boot LUN and the other 2 HBAs are treated as another host and connect to storage group with data LUNs.