high availability, maximum message length, shared queues, queue-sharing group, maximum length for shared queues, messages, amount of data held, Coupling Facility (CF), Coupling Facility structures, CF structures" /> The Coupling Facility

 

The Coupling Facility

The messages held on shared queues are actually stored inside a Coupling Facility. The Coupling Facility lies outside any of the z/OS images in the sysplex and is typically configured to run on a different power supply. The Coupling Facility is therefore resilient to software failures and we can configure it so that it is resilient to hardware failures or power-outages. This means that messages stored in the Coupling Facility are highly available.

Each Coupling Facility list structure used by WebSphere MQ is dedicated to a specific queue-sharing group, but a Coupling Facility can hold structures for more than one queue-sharing group. Queue managers in different queue-sharing groups cannot share data. Up to 32 queue managers in a queue-sharing group can connect to a Coupling Facility list structure at the same time.

A single Coupling Facility list structure can contain up to 512 shared queues. The amount of message data is limited by the size of the list structure. The size of the list structure is restricted by the following factors: