A primary goal of Parallel Sysplex® is continuous availability. Therefore, it is a requirement that changes such as new applications, software, or hardware can be introduced non-disruptively, and that they be able to coexist with current levels. In support of compatible change, the hardware and software components of the Parallel Sysplex solution will allow the coexistence of two levels, that is, level N and level N+1. This means, for example, that no IBM® software product will make a change that cannot be tolerated by the previous release.