Thank you Ariel.
I have come across couple of issues while making a LUN online and accessible. Here is the issue and fix for my issue:
1. LUN created and assigned to a Windows host
2. On Windows 2008R2 OS, command prompt -> diskpart
diskpart> SAN policy (Shows the SAN policy set as offline)
diskpart> SAN policy=onlineall
diskpart> SAN policy (Shows the policy available as online)
3. Rescan the disks from "DIsk Management" prompt and was able to view the LUN as disk.
4. Though disk was online this time, server stopped me from initializing the disk as disk property was set to Read-only
5. From "Diskpart>" prompt,
diskpart> list disk (Lists all the disks availble on the server with numbers)
diskpart> select disk n (Where n is the disk number you want to access)
diskpart> attributes disk
diskpart> attributes disk clear readonly
diskpart> attributes disk Readonly option should be set to "NO" now)
6. From disk management, right click on the LUN (disk device) and select suitable option.
This clears my issue and enabled me to access the LUN from Windows 2008 R2.