def validate_description(cls, desc):
        desc = str(desc)
        # We cannot fail when the description is too long, since we must
        # support older engine that may send such values, or old disks
        # with long description.
        if len(desc) > sc.DESCRIPTION_SIZE:
            cls.log.warning("Description is too long, truncating to %d bytes",
                            sc.DESCRIPTION_SIZE)
            desc = desc[:sc.DESCRIPTION_SIZE]
        return desc