'Return disk type corresponding to the extra_spec disk type.
:param extra_spec_disk_type: disk type in extra_spec
:return: virtual disk type
:raises: InvalidDiskTypeException'

@staticmethod
def get_virtual_disk_type(extra_spec_disk_type):

    VirtualDiskType.validate(extra_spec_disk_type)
    return VirtualDiskType.EXTRA_SPEC_DISK_TYPE_DICT[extra_spec_disk_type]
