CLWLPRTY queue attribute
The CLWLPRTY queue attribute specifies the priority of local, remote, or alias queues 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 queue attribute to set a preference for destination queues. 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, you can use this attribute to allow failover. The highest priority queue manager receives requests, lower priority queue managers act as reserves. If the highest priority queue manager fails, then the next highest priority queue manager that is available, takes over.
IBM MQ obtains the priority of queue managers after checking channel status. Only available queue managers are candidates for selection.
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.
If you need 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 backup.