Choosing a primary installation

On systems that support multiple installations of IBM® WebSphere® MQ (UNIX, Linux®, and Windows), the primary installation is the one to which IBM WebSphere MQ system-wide locations refer. Having a primary installation is optional, but convenient.

Before IBM WebSphere MQ Version 7.1, only one instance of the product could be installed at any time. On Windows systems, several global environment variables were set to point to that installation. On UNIX and Linux systems, symbolic links were added to /usr/lib, /usr/bin, and /usr/include, also pointing at that single installation.

From Version 7.1, you can install multiple versions of IBM WebSphere MQ on UNIX, Linux, and Windows. It is possible to have more than one installation of IBM WebSphere MQ on one of these systems at any time and, optionally, to configure one of these installations as the primary installation. Environment variables and symbolic links pointing to a single installation are less meaningful when multiple versions exist. However, some functions require these system-wide locations to work. For example, custom user scripts for administering IBM WebSphere MQ, and third party products. These functions work only on the primary installation.

On UNIX and Linux systems, if you set an installation as the primary installation, symbolic links to the external libraries and control commands of that installation are added into /usr/lib, and /usr/bin. If you do not have a primary installation, the symbolic links are not created. For a list of the symbolic links that are made to the primary installation, see External library and control command links to primary installation on UNIX and Linux.

On Windows systems, the global environmental variables point to the directories into which the primary installation was installed. These environment variables are used to locate IBM WebSphere MQ libraries, control commands, and header files. Additionally, on Windows systems, some features of the operating system require the central registration of interface libraries that are then loaded into a single process. With multiple versions of IBM WebSphere MQ, there would be conflicting sets of IBM WebSphere MQ libraries. The features would try to load these conflicting sets of libraries into a single process. Therefore, such features can be used only with the primary installation. For details about some of the features that are limited to use with the primary installation, see Features that can be used only with the primary installation on Windows.

If you have an installation of IBM WebSphere MQ Version 7.0.1 on the system, this installation is automatically the primary installation. The primary installation cannot be changed while Version 7.0.1 is installed. If all the installations on the system are at Version 7.1, or later, you can choose whether to have a primary installation. Consider the options in Table 1.
Table 1. Primary installation options.

This table shows the valid installation configurations for primary installations. With a single Version 7.1, or later, it can be either primary, or non-primary. With multiple installations, one at Version 7.0.1 and one or more at Version 7.1, or later,Version 7.0.1 must be the primary, and the other installations must be non-primary. With multiple installations at Version 7.1, or later, one installation can be primary, or all installations can be non-primary.
Options Valid installation configurations More information
  Primary Non-primary  
Single installation of Version 7.1, or later. Version 7.1, or later. None If you want to continue working with a single installation in the same way as previous releases, configure your installation as the primary installation. For information about this option, see Single installation of IBM WebSphere MQ Version 7.1, or later, configured as the primary installation
None Version 7.1, or later. If you want to continue working with a single installation, but do not want symbolic links or global environment variables created for you, configure your installation as non-primary. For information about the implications of this option, see Single installation of IBM WebSphere MQ Version 7.1, or later, configured as non-primary

Multiple installations:

Version 7.0.1 and Version 7.1, or later.

 Version 7.0.1 Version 7.1, or later. If you want to have multiple installations of IBM WebSphere MQ, with one at version 7.0.1, the version 7.0.1 installation is automatically the primary installation. While IBM WebSphere MQ version 7.0.1 is installed, you cannot change which installation is the primary installation. For information about this option and its implications, see Multiple installations of IBM WebSphere MQ, one at Version 7.0.1

Multiple installations:

Version 7.1, or later.

 Version 7.1, or later. Version 7.1, or later. If you want to have multiple installations of WebSphere MQ at version 7.1 or greater, you can choose whether to make one of the installations primary. For information about this option, see Multiple installations of IBM WebSphere MQ Version 7.1, or later
None Version 7.1, or later.