Rolling z/OS across a multisystem configuration
A rolling IPL is the IPL of one system at a time in a multisystem configuration. You might stage the IPLs over a few hours or a few weeks. The use of rolling IPLs allows you to migrate each z/OS® system to a later release, one at a time, while allowing for continuous application availability.
For example, data sharing applications offer continuous availability in a Parallel Sysplex® configuration by treating each z/OS system as a resource for processing the workload. The use of rolling IPLs allows z/OS systems running these applications to be IPLed one at a time, to migrate to a new release of z/OS, while the applications continue to be processed by the other z/OS systems that support the workload. By using LPAR technology, you can use rolling IPLs to upgrade your systems without losing either availability or capacity.
- The release to which you are migrating is supported for coexistence, fallback, and migration with the releases running on the other systems. See Which releases are supported for coexistence, fallback, and migration? for the releases that are supported.
- The appropriate coexistence PTFs have been installed on the other systems in the multisystem configuration.
Even when you are using applications that do not support data sharing, rolling IPLs often make it easier to schedule z/OS software upgrades. It can be very difficult to schedule a time when all applications running on all the systems in a multisystem configuration can be taken down to allow for a complex-wide or Parallel Sysplex-wide IPL.
The use of rolling IPLs not only enables continuous availability from an end-user application point of view, but it also eliminates the work associated with migrating all z/OS systems in a multisystem configuration at the same time.