Each secondary partition on an iSeries™ server acts as an independent system on the server.
However, these partitions maintain a dependency on the primary partition. It must be running to keep each secondary partition on the system accessible. With that in mind, deciding on what runs in the primary partition is important to maintain stability throughout your system.
If you have multiple production environments on the same server, it is recommended to configure the primary partition with the minimum amount of hardware resources and if necessary use the primary only for applications that are stable.
Secondary partitions can handle different types of workload demands without causing down time on the server. You can perform fixes or new release testing on secondary partitions before installing these packages to the primary partition. Applications that require high availability should be running in a secondary partition to minimize problems with the applications. You can also use the secondary partition to back-up data on another partition on the server. This way if data is lost the secondary partition responsible for backing up the information can be used without causing delays to your business schedule.