How to present 6TB of LUN to Windows Server

I attached 6TB of ISCSI lun to my VCB backup server and after attaching this is  what I found under diskmgmt.msc

I then checked if the VOL has been split across by SAN admin but that was not the case. This was the part of same VOL so why does WIN2K3 show it as two VOL of 2 and 4TB.

After that I realize with MBR I can have only 2TB of lun and if I need to get all 6TB of LUN I need to convert the disk into GPT(GUID Partition Table).

How to do it  ? Just right click on the disk and you will get option “convert to GPT disk”

What I have read and understood is

MBR is the standard partitioning scheme that's been used on hard disks since the PC first came out. It supports 4 primary partitions per hard drive, and a maximum partition size of 2TB.

GPT disks are new, and are readable only by Windows Server 2003 SP1, Windows Vista (all versions), and Windows XP x64 Edition. The GPT disk itself can support a volume up to 2^64 blocks in length. (For 512-byte blocks, this is 9.44 ZB - zettabytes. 1 ZB is 1 billion terabytes). It can also support theoretically unlimited partitions.

Windows restricts these limits further to 256 TB for a single partition (NTFS limit), and 128 partitions.

Only Itanium systems running Windows Server 2003 and Windows Vista systems with an EFI BIOS can boot from a GPT disk. The other operating systems mentioned earlier can use GPT disks as data disks but not boot disks.

To find out more about GPT read this article from MS.