SAP systems are upgraded with the System Switch Upgrade procedure. This procedure installs an instance of the target release, the shadow system, in parallel with the current source release system in the same database. The parallel system contains all the software of the target release and is used to perform actions on the target release while the source release is still in production operation.

Operating two instances in parallel places increased demands on free space in the file system, in the database, and on the system resources. No precise guidelines can be given for the duration of an upgrade. The duration of the shadow system installation depends on a great extent on the amount of data, the database system, and the hardware and can take several hours. Although the system can still be used in production operation, consider a possible performance decrease during this shadow system installation process. If necessary, some parameters in the production system must be adjusted to enable you to operate the production and the shadow systems in parallel.

The following figure shows the process flow of the upgrade with the major steps of the process.

The complete upgrade procedure is divided into roadmap steps. In these roadmap steps, the following actions take place:

• Get Roadmap

  The Software Update Manager analyzes the source system and the database, and it collects by means of a dialog sequence the needed information for the wanted scenario to assemble the roadmap.

• Extraction

  The Software Update Manager extracts the required software.

• Configuration

  In this roadmap step, you enter information required for the upgrade procedure such as information about software components, add-ons, and support packages that you want to include as well as information about the shadow system.

• Checks

  The Software Update Manager checks if the operating system and database version of your source release match the requirements of the target release. It also checks some application-specific requirements.

• Preprocessing

  In the Preprocessing roadmap step, the Software Update Manager creates the shadow system. This roadmap step requires only few user entries. And during the roadmap step, both the substitution table import and the shadow system operation start.

  When the roadmap step is finished and you choose Next, the downtime starts.

• Execution

  This roadmap step runs without any user interaction. While the processes of the Execution roadmap step are running, the system is in downtime. The switch to the new system takes place in this roadmap step. The Software Update Manager converts application tables and data to match the target release layout. In addition, it switches the SAP kernel.

• Postprocessing

  The Software Update Manager saves the log files and prompts you to start with certain follow-up activities.

• Finalization and Summary

  The Software Update Manager removes files and directories that are no longer required and completes the upgrade. Moreover, it displays a feedback form on the SUM UI and prompts you to send your feedback to SAP for technical analysis. For more information, see Evaluating the Software Update Manager.