The Intelligent Resource Director (IRD) extends the concept of goal-oriented resource management by allowing you to group logical partitions that are resident on the same physical server, and in the same sysplex, into an "LPAR cluster." This gives WLM the ability to manage resources, both processor and DASD I/O, not just in one single image but across the entire cluster of logical partitions.
See The Intelligent Resource Director for more information.