Restoring a queue manager from the latest version to a previous version on UNIX systems and Windows

You can restore a queue manager to the previous version of the product from the latest version, if you have made a backup of the system or queue manager. If you have started the queue manager and processed any messages, or changed the configuration, the task cannot give you any guidance on restoring the current state of the queue manager.

Before you begin

You must have made a backup of the system or queue manager before you upgraded to the latest version. For more information see Backing up and restoring IBM® MQ queue manager data
If any messages were processed after starting the queue manager, you cannot easily undo the effects of processing the messages. You cannot restore the queue manager to the previous version of the product in its current state. The task cannot give you any guidance how to deal with subsequent changes that have occurred. For example, messages that were indoubt in a channel, or in a transmission queue on another queue manager, might have been processed. If the queue manager is part of a cluster, then configuration messages and application messages might have been exchanged.
If you are running on a server with multiple IBM MQ installations, you must identify the installation. Make sure that the commands you enter run against the correct installation; see setmqenv.

About this task

When you restore a previous version of a queue manager, you restore the queue manager to its earlier code level. Queue manager data is restored to the state it was in when the queue manager was backed up.

Important: If the queue manager is a member of one or more IBM MQ clusters, you should also review and follow the steps described in Recovering a cluster queue manager.

Procedure

Log in as a user in group mqm.
Stop all applications using the IBM MQ installation.
If you use the MQ Managed File Transfer (MFT) component, ensure that any MFT agents have finished all of the file transfers that they were engaged in. There should be no incomplete transfers associated with the agents, and their SYSTEM.FTE.STATE queues should contain no messages.
End all the activity of queue managers associated with the IBM MQ installation.
1. Run the dspmq command to list the state of all the queue managers on the system.
  Run either of the following commands from the installation that you are updating:
```
dspmq -o installation -o status
dspmq -a
```
  dspmq -o installation -o status displays the installation name and status of queue managers associated with all installations of IBM MQ.
  
  dspmq -a displays the status of active queue managers associated with the installation from which the command is run.
2. Run the MQSC command, DISPLAY LSSTATUS(*) STATUS to list the status of listeners associated with a queue manager.
```
echo "DISPLAY LSSTATUS(*) STATUS" | runmqsc QmgrName
```
3. Run the endmqm command to stop each running queue manager associated with this installation.
  The endmqm command informs an application that the queue manager it is connected to is stopping; see Stopping a queue manager.
  - For the maintenance to proceed, applications must respond to an endmqm command by disconnecting from the queue manager and releasing any IBM MQ libraries they have loaded. If they do not, you must find another way to force applications to release IBM MQ resources, such as by stopping the applications.
  - You must also stop applications that are using the client libraries that are part of the installation. Client applications might be connected to a different queue manager, running a different installation of IBM MQ. The application is not informed about queue managers in the current installation being shut down.
  - Any applications that continue to have IBM MQ shared libraries from the installation loaded prevent you applying IBM MQ maintenance. An application might disconnect from a queue manager, or be forcibly disconnected, but keep an IBM MQ shared library loaded.
  Note: The topic, Applying maintenance level updates to multi-instance queue managers, describes how to apply maintenance to a multi-instance queue manager. A multi-instance queue manager can continue to run on one server, while maintenance is applied to another server.
4. Stop any listeners associated with the queue managers, using the command:
```
endmqlsr -m QMgrName
```
Restore the system, or IBM MQ and the queue manager.

If your backup procedure was to save the queue manager data, you must reinstall IBM MQ.
1. Uninstall the previous installation.
2. Reinstall IBM MQ from a manufacturing refresh.
3. Apply the fix pack and interim fixes that restore IBM MQ to its previous level.
4. Restore the queue manager data from the backup taken before installing the latest version.
Restart the previous version queue manager.

What to do next

You might be restoring a previous version on a server with multiple IBM MQ installations. If one of the installations is primary, after restoring the previous version that installation, by default, becomes the primary installation.

You must review how applications connect to an installation. After restoring the previous version, some applications might connect to the wrong installation.