You can connect a messaging engine to a WebSphere MQ queue manager so that, to WebSphere MQ, the messaging engine appears to be another queue manager. If you connect a messaging engine in this way, there are some high availability considerations that you need to take into account.
If the messaging engine fails over to a different server, this will break the connection between the WebSphere MQ queue manager and the messaging engine. The WebSphere MQ queue manager uses a configured IP address and port to reach the messaging engine, so you must ensure that the messaging engine is still accessible using that IP address. The IP address must therefore also be failed over to the machine that is running the server to which the messaging engine has moved. This can be achieved by creating resources for the messaging engine and IP address in a resource group managed by an external high availability framework.
Any messaging engine that needs to remain highly available to a WebSphere MQ queue manager must therefore be controlled by a 'No operation' policy. The messaging engine's data store can be located in the same external high availability resource group as the resource which represents the messaging engine.