Methods of serializing global resources

A global resource serialization complex is one or more z/OS® systems that use global resource serialization to serialize access to shared resources (such as data sets on shared DASD volumes). In this document, the term sysplex refers to a multisystem sysplex. It is possible, in a ring configuration, to have systems in a global resource serialization complex that are not in the sysplex. For the purposes of global resource serialization, these systems should be treated as if they are not part of a multisystem sysplex. The ring and star systems cannot coexist in a global resource serialization complex.

Every system in a sysplex is a member of the same global resource serialization complex. Global resource serialization is required in a sysplex because components and products that use sysplex services need to access a sysplex-wide serialization mechanism. For more information on sysplexes, see the following topics:

Multisystem sysplex configuration without an existing global resource serialization complex
Multisystem sysplex configuration with an existing global resource serialization complex

in z/OS MVS Setting Up a Sysplex.

You can set up either of the following complexes for global resource serialization:

A star - In this type of complex, all of the systems in the sysplex must match the systems in the complex.
A ring - In this type of complex, either:
- The systems in the sysplex are the same as the systems in the complex (sysplex matches complex). In a ring, you derive greater benefits if the sysplex and the complex match.
- At least one system in the complex is outside of the sysplex (mixed complex). A mixed complex often exists temporarily as your installation migrates one system at a time into a star complex.

The ring is IBM's original design for serializing global resources and it still has value in today's sysplex environment. But the star offers many advantages over the ring complex. Which method to choose offers guidance on which method best suits your present environment and future needs.