Maintaining a queue manager in a cluster

Suspend and resume a queue manager from a cluster to perform maintenance.

About this task

From time to time, you might need to perform maintenance on a queue manager that is part of a cluster. For example, you might need to take backups of the data in its queues, or apply fixes to the software. If the queue manager hosts any queues, its activities must be suspended. When the maintenance is complete, its activities can be resumed.

Procedure

Suspend a queue manager, by issuing the SUSPEND QMGR runmqsc command:
```
SUSPEND QMGR CLUSTER(clusterName)
```
Where clusterName specifies the name of the cluster.

The SUSPEND runmqsc command notifies the queue managers in the cluster that this queue manager has been suspended.

The purpose of the SUSPEND QMGR command is only to advise other queue managers to avoid sending messages to this queue manager if possible. It does not mean that the queue manager is disabled. Some messages that have to be handled by this queue manager are still sent to it, for example when this queue manager is the only host of a clustered queue.

While the queue manager is suspended the workload management routines avoid sending messages to it. Messages that have to be handled by that queue manager include messages sent by the local queue manager.

IBM® MQ uses a workload balancing algorithm to determine which destinations are suitable, rather than selecting the local queue manager whenever possible.
1. Enforce the suspension of a queue manager by using the FORCE option on the SUSPEND QMGR command:
```
SUSPEND QMGR CLUSTER(clusterName) MODE(FORCE)
```
  Where clusterName specifies the name of the cluster.
  
  MODE(FORCE) forcibly stops all inbound channels from other queue managers in the cluster. If you do not specify MODE(FORCE), the default MODE(QUIESCE) applies.
For more information, see SUSPEND QMGR.
Check that no messages are sent to the queue manager.

You must close any application that continues to send messages to this queue manager. The cluster workload algorithm might choose the suspended queue manager. If there are no other valid destinations, or if an application has an affinity with the queue manager, it might select the queue manager.
Do whatever maintenance tasks are necessary.
Resume the queue manager by issuing the RESUME QMGR runmqsc command:
```
RESUME QMGR CLUSTER(clusterName)
```
Where clusterName specifies the name of the cluster.

Results

The RESUME runmqsc command notifies the full repositories that the queue manager is available again. The full repository queue managers disseminate this information to other queue managers that have requested updates to information concerning this queue manager.