Cluster repositories

A cluster repository contains information about the cluster; for example, information about the queue managers that are members of the cluster, and the cluster channels. Repositories are hosted by the queue managers in the cluster.

Normally, to ensure availability, two queue managers (on different computers) host full repositories, which contain a complete set of information about the cluster and its resources. The two queue managers exchange messages to keep their repositories synchronized. All the other queue managers in the cluster host partial repositories, which contain an incomplete set of information about the cluster and its resources.

A queue manager's partial repository contains only information about the queue managers with which the queue manager needs to exchange messages. The queue manager requests updates from the full repositories so that if the information changes, the full repository queue managers sends them the new information. For much of the time a queue manager's partial repository has all the information it needs to perform within the cluster. When a queue manager needs some additional information, it makes inquiries of the full repository and updates its partial repository.

Two special types of channel are used by each queue manager for this purpose, one each of cluster-sender (CLUSSDR) and cluster-receiver (CLUSRCVR).

DHCP

If a computer uses DHCP (dynamic allocation of IP address), you are recommended to define the repository's Connection name attribute using the computer's name instead of the computer's IP address. This is because the connection name is used to find the repository. If the computer's IP address is used and the IP address subsequently changes, other queue managers will no longer be able to find the repository. This still applies even if all the queue managers in the cluster are on the same computer, because the IP address is still used to find the repository.