Windows 2012 cluster validation wizard disk failed GPT disk

To change a GUID partition table disk into a master boot record disk using command line
Back up or move all volumes on the basic GUID partition table (GPT) disk you want to convert into a master boot record (MBR) disk.

1. Open an elevated command prompt and type diskpart. If the disk does not contain any partitions or volumes, skip to step 6.
2. At the DISKPART prompt (right-click Command Prompt, and then click Run as Administrator), type list disk. Make note of the disk number you want to delete.
3. At the DISKPART prompt, type select disk <disknumber>.
4. At the DISKPART prompt, type clean.

To change a GUID partition table disk into a master boot record disk using the Windows interface

1. Back up or move all volumes on the basic GUID partition table (GPT) disk you want to convert into a master boot record (MBR) disk.
2. If the disk contains any partitions or volumes, right-click any volumes on the disk and then click Delete Volume.
3. Right-click the GPT disk that you want to change into an MBR disk, and then click Convert to MBR disk.