Primary installation on AIX, Linux, and Windows

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

You can install multiple versions of IBM MQ on AIX, Linux, and Windows. You can have more than one installation of IBM MQ on one of these systems at any time and, optionally, 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 MQ, and third party products. These functions work only on the primary installation.

[AIX] [Linux] On AIX 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 AIX and Linux.

[Windows] On Windows systems, the global environmental variables point to the directories into which the primary installation is installed. These environment variables are used to locate IBM 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 MQ, there would be conflicting sets of IBM 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 more information, see Features that can be used only with the primary installation on Windows.

Table 1. Primary installation options
Options	Valid installation configurations		More information
	Primary	Non-primary
Single installation	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 more information, see Single installation of IBM MQ configured as the primary installation.
Single 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 more information,, see Single installation of IBM MQ configured as non-primary.
Multiple installations	Version 7.1 or later	Version 7.1 or later	If you want to have multiple installations of IBM MQ, you can choose whether to make one of the installations primary. For more information, see Multiple installations of IBM MQ.
Multiple installations	None	Version 7.1 or later.