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Migrating from a single instance to a multi-instance queue manager on IBM i

To migrate a single instance queue manager to a multi-instance queue manager, on IBM i, we must move the queue manager data to a shared directory, and reconfigure the queue manager on two other servers.


Before starting

We must check the prerequisites for running a multi-instance queue manager as part of this task. Some environments have been tested with multi-instance queue managers, and are known to work. IBM i has been tested with multi-instance queue managers and is known to work. For a list of tested environments, see Testing statement for IBM MQ multi-instance queue manager file systems. The support statement has detailed version and prerequisite information for each environment it lists. Other environments might work; a test tool is provided with IBM MQ to assist you in qualifying other environments.

We must have three servers to run a multi-instance queue manager. One server has a shared file system to store the queue manager data and logs. The other servers run the active and standby instances of the queue manager.


About this task

We have a single-instance queue manager that we want to convert to a multi-instance queue manager. The queue manager conversion itself is straightforward, but we must do other tasks to create a fully automated production environment.

We must check the prerequisites for a multi-instance queue manager, set up the environment and check it. We must set up a monitoring and management system to detect if the multi-instance queue manager has failed and been automatically restarted. We can then find out what caused the restart, remedy it, and restart the standby. We must also modify applications, or the way applications are connected to the queue manager, so that they can resume processing after a queue manager restart.


Procedure

  1. Check the operating system that we are going to run the queue manager on, and the file system on which the queue manager data and logs are stored on. Check that they can run a multi-instance queue manager.
    1. Consult Testing statement for IBM MQ multi-instance queue manager file systems. See whether the combination of operating system and file system is tested and capable of running a multi-instance queue manager.

      • A shared file system must provide lease-based locking to be adequate to run multi-instance queue managers. Lease-based locking is a recent feature of some shared file systems, and in some case fixes are required. The support statement provides you with the essential information.

    2. Run amqmfsck to verify that the file system is configured correctly.

      • File systems are sometimes configured with performance at a premium over data integrity. It is important to check the file system configuration. A negative report from the amqmfsck tool tells you the settings are not adequate. A positive result is an indication that the file system is adequate, but the result is not a definitive statement that the file system is adequate. It is a good indication.

    3. Run the integrity checking application provided in the technote, Testing a shared file system for compatibility with IBM MQ Multi-instance Queue Managers.

      • The checking application tests that the queue manager is restarting correctly.

  2. Configure a user and group to be able to access a share on the networked file system from each server that is running a queue manager instance. On IBM i, QMQM, QMQMADM, and any other user profiles that are granted access to the share must have the same passwords on all the servers
  3. Set up a directory for the share on the networked file system with the correct access permissions.

    • For example, create a root directory on the share called MQHA that has subdirectories data and logs. Each queue manager creates its own data and log directories under data and logs. Create MQHA with the following properties:
    • On IBM i, follow the instructions to create a network share using NetServer.

  4. Copy the queue manager data and the logs to the share.

    • We can choose to copy files manually, by following the procedure to back up the queue manager. elect one of these methods:

    • Follow the instructions in Backups of IBM MQ for IBM i data, copying the queue manager data to the share. We must use this method if the DataPath configuration attribute is specified for this queue manager.
    • Stop the queue manager, and then type the command, 
      hamvmqm /m /dd share\data /dd share\logs
      Where share is to be the location of the data and logs that you created in step 3.

  5. Update the queue manager configuration information stored on the current queue manager server.

    • If you moved the queue manager data and logs by running the hamvmqm command, the command has already modified the configuration information correctly for you.
    • If you moved the queue manager data and logs manually, we must complete the following steps.

    • On IBM i,
      1. Modify the Log: stanza in the queue manager qm.ini file, which is on the share : 
        LogPath= share/logs/QMgrName
      2. Modify the QueueManager: stanza in the IBM MQ mqs.ini file, which is typically in the /QIBM/UserData/mqm directory on IBM i: 
        DataPath= share/data/QMgrName

    Where, QMgrName is the Directory name in the QueueManager: stanza in the mqs.ini file on IBM i. share is share where the data and logs are moved to.

  6. Add the queue manager configuration information to the new queue manager server.
    1. Run the dspmqinf command to display the queue manager information

      • Run the command on the server that ran the queue manager in Version 6.0. 

      dspmqinf -o command QMgrName

      The command output is formatted ready to create a queue manager configuration.

      addmqinf -s QueueManager -v Name= QMgrName -v Directory= QMgrName -v Prefix=d:\var\mqm Datapath= \share\data\QMgrName
    2. Create a queue manager configuration on the other server.

      • Run the addmqinf command copied from the previous output

  7. Add the network address of the new server to the connection name in client and channel definitions.
    1. Find all the client, sender, and requester TCPIP settings that refer to the server.

      • Client settings might be in Client Definition Tables (CCDT), in environment variables, in Java properties files, or in client code.
      • Cluster channels automatically discover the connection name of a queue manager from its cluster receiver channel. As long as the cluster receiver channel name is blank or omitted, TCPIP discovers the IP address of the server hosting the queue manager.

    2. Modify the connection name for each of these connections to include the TCPIP addresses of both servers that are hosting the multi-instance queue manager.

      • For example, change: 

      echo DISPLAY CHANNEL(ENGLAND) CONNAME | runmqsc QM1

      5724-H72 (C) Copyright IBM Corp. 1994, 2020.  ALL RIGHTS RESERVED.


Starting MQSC for queue manager QM1.


1: DISPLAY CHANNEL(ENGLAND) CONNAME


AMQ8414: Display Channel details.


CHANNEL(ENGLAND) CHLTYPE(SDR)


CONNAME(LONDON)

      • Into: 

      echo ALTER CHANNEL(ENGLAND) CHLTYPE(SDR) CONNAME('LONDON, BRISTOL') | runmqsc QM1

  8. Update your monitoring and management procedures to detect the queue manager restarting.
  9. Update client applications to be automatically reconnectable, if appropriate.
  10. Update the start procedure for the IBM MQ applications to be started as queue manager services.
  11. Start each instance of the queue manager, permitting them to be highly available.

    • The first instance of the queue manager that is started becomes the active instance.
    • Issue the command twice, once on each server. 

    strmqm -x QMgrName


What to do next

To get the highest availability out of multi-instance queue managers, we must design client applications to be reconnectable and server applications to be restartable; see Application recovery.

Parent topic: Migrating IBM MQ on IBM i


Related information

Last updated: 2020-10-04