## 2.1 Scenarios 

Throughout this book, we use two distinct scenarios by which we explain the tasks and procedures involved to successfully install and configure a z15 server. 

## 2.1.1 Scenario 1: Upgrading an existing IBM Z server to a z15 

This scenario assumes that an existing IBM Z environment where the existing IBM Z server is upgraded by using a miscellaneous equipment specifications (MES) to a z15. The scenario includes a planned outage period for the time of the physical upgrade of the machine. The software environments that are supported by this machine will not be available during this period. The serial number of the machine will remain the same after the upgrade. 

## 2.1.2 Scenario 2: Installing a new z15 server 

This scenario assumes that a new z15 is installed in an existing mainframe environment. The z15 machine will be physically installed along with an existing IBM Z machine. After the installation of the z15 has been successfully completed and the system has been handed over by the IBM service representative, the software environment on the machine to be replaced must be stopped and recabling actions must be performed. 

When recabling is complete, post installation activities must be performed and the software environment can be brought back online on the new system (z15). An outage has still to be planned for this scenario, and a new serial number must be considered, so software keys for the new system must be available. 

## 2.1.3 Differences in planning for the two scenarios 

In the first scenario, the physical platform identity to be configured remains the same. No hardware configuration files must be physically migrated to another platform. The machine serial number remains the same after the upgrade, so no changes to the software licenses are required. 

In the second scenario, the physical platform to be configured changes. Hardware configuration files must be prepared on the existing machine, and must be migrated (moved) to the new z15 server together with the attached cabling. The serial number changes with the activation of the z15 machine, which means that planning and preparing for software license changes must be considered. 

In both scenarios, we assume that bringing up the existing features and functions has highest priority. Adding new features and functions (new functionality) acquired with the system upgrade or installed in the new z15 have a lower priority. The elapsed time of the planned outage can vary significantly, depending on the approach chosen in either scenario. 

