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CLWLPRTY channel attribute

The CLWLPRTY channel attribute specifies the priority order for channels for cluster workload distribution. The value must be in the range 0-9, where 0 is the lowest priority and 9 is the highest.

Use the CLWLPRTY channel attribute to set a priority order for the available cluster destinations. IBM MQ selects the destinations with the highest priority before selecting destinations with the lowest cluster destination priority. If there are multiple destinations with the same priority, it selects the least recently used destination.

If there are two possible destinations, we can use this attribute to allow failover. Messages go to the queue manager with the highest priority channel. If it becomes unavailable then messages go to the next highest priority queue manager. Lower priority queue managers act as reserves.

IBM MQ checks channel status before prioritizing the channels. Only available queue managers are candidates for selection.

Notes:

  • Specify this attribute on the cluster-receiver channel at the target queue manager. Any balancing you specify on the matching cluster-sender channel is likely to be ignored. See Cluster channels.
  • The availability of a remote queue manager is based on the status of the channel to that queue manager. When channels start, their state changes several times, with some of the states being less preferential to the cluster workload management algorithm. In practice this means that lower priority (backup) destinations can be chosen while the channels to higher priority (primary) destinations are starting.
  • For to ensure that no messages go to a backup destination, do not use CLWLPRTY. Consider using separate queues, or CLWLRANK with a manual switch over from the primary to back up.

Parent topic: Workload balancing in clusters


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Last updated: 2020-10-04