Your choice of method, ring or star, depends primarily on hardware requirements.

• The star complex hardware requirements:
  • Coupling facility
  • Coupling facility links
• The ring hardware requirements:
  • Communications links, XCF sysplex, or both

It is also important the consider the number of systems in the global resource serialization complex, and what performance you are experiencing. IBM® recommends that:

• New sysplexes start out using the star method for serializing global resources.
• Complexes that require sharing the MVS™ systems that are not members of a sysplex require using the ring.
• Existing complexes experiencing performance problems should migrate to the star.