SnapDrive supports the GUID partition table (GPT) partitioning style on new LUNs created by SnapDrive when you have Data ONTAP 7.2.6 or later installed on your storage system.
GPT shared LUNs are supported with Windows Server 2008 and with Windows Server 2003 when Microsoft hotfix 919117 is installed.
Neither SnapDrive nor Data ONTAP support MBR LUNs that are converted to GPT-style LUNs. If you have an existing MBR-style LUN, rather than converting, you must create a new GPT LUN using SnapDrive, then copy all the data from the MBR LUN to the GPT LUN.