Microsoft suggested solution:

-Create new 4.8TB, convert this right away to “GPT disk” during first disk initialization at Windows 2008 R2 (assign as temporal drive letter say “X”)

-Shutdown database

-Robocopy the existing L drive (1.7TB) data to new drive 4.8TB

-Dismount 1.7TB (MBR disk) from L drive

-Mount 4.8TB (GPT disk) to L drive

-Start-up database & perform application check.

I have updated the MS solution here, if anyone encounters the same situation - they can use it.

Thanks!