The CLUS_STORAGE_REMAP_DRIVELETTER structure identifies the existing and target drive letter for a disk drive on a node.
CLUS_STORAGE_REMAP_DRIVELETTER is a custom-marshaled structure that has fields as follows.
CurrentDriveLetterMask (4 bytes): A 32-bit bitmask indicating the drive letter to be changed. The least significant bit represents the drive letter 'A' through bit 25, which represents the drive letter 'Z'.
TargetDriveLetterMask (4 bytes): A 32-bit bitmask indicating the new drive letter for the disk drive that corresponds to the drive letter specified in CurrentDriveLetterMask.