Even though there could be multiple servers and z/OS® images in the Parallel Sysplex® and a mix of different technologies, the collection of systems in the Parallel Sysplex should appear as a single entity to the operator, the end user, the database administrator, and so on. A single system image brings reduced complexity from both operational and definition perspectives.

Regardless of the number of system images and the complexity of the underlying hardware, the Parallel Sysplex solution provides for a single system image from several perspectives:

• Data access, allowing dynamic workload balancing and improved availability
• Dynamic Transaction Routing, providing dynamic workload balancing and improved availability
• End-user interface, allowing logon to a logical network entity
• Operational interfaces, allowing easier Systems Management

It is a requirement that the collection of systems in the Parallel Sysplex can be managed from a logical single point of control. The term "single point of control" means the ability to access whatever interfaces are required for the task in question, without reliance on a physical piece of hardware. For example, in a Parallel Sysplex of many systems, it is necessary to be able to direct commands or operations to any system in the Parallel Sysplex, without the necessity for a console or control point to be physically attached to every system in the Parallel Sysplex.

Even though individual hardware elements or entire systems in the Parallel Sysplex fail, a single system image must be maintained. This means that, as with the concept of single point of control, the presentation of the single system image is not dependent on a specific physical element in the configuration. From the end-user point of view, the parallel nature of applications in the Parallel Sysplex environment must be transparent. An application should be accessible regardless of which physical z/OS image supports it.