I have a 1.99TB LUN on an EMC array that is assigned to a Windows 2003 Microsoft x64 cluster. I have expanded the LUN on the array side to 3TB. Using disk management I am able see the available space on the disk in question. I also know that converting the disk to GPT has to be done through diskpart, hotfix 919117 is installed and there are no partitions on the drive but, there is data. My question is would I lose the existing data if I converted the disk to GPT?