This section introduces the Impact Analysis. Impact Analysis works based on (production) statistical data and Software Update Manager (SUM) table classification data to help determine potential impacts on business processes during a Zero Downtime Option (ZDO) maintenance event.
Running an upgrade using a downtime-optimization approach can result in certain kinds of impacts for the ongoing business operations on the bridge subsystem. Hence, the Impact Analysis is an important step in the preparation of the ZDO procedure.
In the case of ZDO, the following impacts are checked by the Impact Analysis:
- Read-only restrictions for end users on the bridge instance
- Database triggers might have to be removed from certain tables or an initial load is needed after the completion of the upgrade
- Additional database space needed for the clone tables
- Tables that will be smart-switched but have a high number of changes
To prevent unexpected occurrence of such impacts during the maintenance event on your production system, you would like to identify them in advance. This can be achieved by exporting table statistics from your production system and providing them to the Software Update Manager in your very first cycle running in a sandpit environment. The Impact Analysis is equipped with the capabilities to give a projection on "what would happen if the defined upgrade scope would be applied in the production system?"
It is important to understand that the results of the Impact Analysis are based on these facts:
- The defined scope (list of software components as well as the source and target levels of the software components versions) must be identical in all systems that should be upgraded in your project. When changing the stack definition, the results will be different and need to be interpreted again.
- The exported table statistics should be representative of the time the business operations will work on the bridge subsystem. All relevant business processes should be captured accordingly in the exported statistics file.
SAP Notes Related to Impact Analysis for Zero Downtime Option:
The analysis is based on statistical data retrieved from the productive system, as only there real end-user activity is happening. To perform the export of the statistical data, the Software Update Manager (SUM) Toolbox has to be available in the productive system. SUM Toolbox is available using TCI SAP Note (TCI: transport-based correction instruction). In addition, the tool will be shipped with the regular software delivery of SAP_BASIS. SUM Toolbox includes a tool which does the export of the statistical table access data. Additionally, a dialog version of the Impact Analysis is included.
The data that is exported using SUM Toolbox is later analyzed by SUM in phase
RUN_IMPACT_ANALYSIS_ZDO. Furthermore, the analysis can be performed in dialog mode using SUM Toolbox like described in the following lessons.
This figure shows the procedure flow at a high-level. All steps will be explain in separate lessons during this unit.
One part of the upgrade procedure is called table classification, which calculates how the tables are handled during the upgrade. This includes both sets of tables: customer-created and SAP-delivered tables. Technically, the table classification happens in phase
The most important table classification types are as follows:
- Share [upgrade does not touch the table or just adds a new non-key field]: These tables will not be cloned. No restrictions apply.
- Clone [that is, upgrade delivers table content or a structural change]: Additional database space required for table clone and change record and replay. No restrictions apply.
- Clone read-only [that is, upgrade delivers a complex structural change or an XPRA accesses the table]: Additional database space required for table clone and change record and replay. Table will be read-only for the business users while working on the bridge subsystem.
Schematic Illustration of the Impact Analysis
Following the example, Table-B will be cloned and set to read-only for the bridge subsystem. This could potentially lead to a business impact for end users working on the bridge subsystem since read-only tables are blocked against write accesses. If the table statistics file (
ZDIMPANA.ZIP) contains the information that the Table-B changed, the Impact Analysis will throw an error. The result needs to be interpreted in a way to see whether the bridge subsystem really needs to write into the table. It is now important to figure out which business processes write into the read-only tables. If the processes are identified it has to be verified with the responsible business process owner and key users whether the read-only constraint can become critical for the business.
Table-D will be cloned as the upgrade will perform a change on the table. However, Table-D will be fully available with read and write accesses for the bridge subsystem. As Table-D will be cloned but has database triggers of type SLT, an error is displayed. After SUM is finished, an initial reload is needed for clones tables with database triggers (for details, see lesson SLT Database Trigger Handling in ZDO of unit 3).
Lastly, Table-D will be smart-switched since the table is being cloned. Tables that will be smart-switched will be renamed on-the-fly in phase EU_SWITCH_ZDM. Dependent on the load, this could impact the SUM tool since renaming tables requires an exclusive table lock on database level.
Further details on how the result of the Impact Analysis should be evaluated and interpreted can be found in lesson Results of the Impact Analysis in unit 4.
Overview on Reports related to Impact Analysis
|Delivered with SUM 2.0 tool import (will be deleted after the upgrade)
|Used by SUM in batch mode in phase
|Tools delivered with SUM Toolbox (SAP Note 3092738)
|Export data for impact analysis
|Export of table statistics of the production system to a compressed file (that is,
|Export of SUM classification data
|Export of table classification data of the Software Update Manager (that is,
|Dialog version of the Impact Analysis, which can be used after completion of phase
RUN_RSPTBFIL_ZDM_CLASSIFY in any system which is upgraded using ZDO with the same software stack
For more information and FAQ, refer to the following blog posts in the SAP Community:
- SAP Community blog Impact Analysis as part of Software Update Manager 2.0 in the SAP Community: https://blogs.sap.com/2018/03/08/impact-analysis-as-part-of-software-update-manager-2.0/
- SAP Community blog Software Update Manager Toolbox is Available Now in the SAP Community: https://blogs.sap.com/2021/12/10/software-update-manager-toolbox-is-available-now/