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This document provides frequently asked questions for near Zero Downtime Maintenance of ABAP based systems.

You find the newest information about the near-Zero Downtime Maintenance (nZDM) for SUM in the SUM 1.0 and 2.0 guides (https://support.sap.com/sltoolset) and in SAP Notes 1678565 - Prerequisites, Terms and Conditions for nZDM/SUM and 1678564 - Restrictions, Database-specific Settings, and Troubleshooting of nZDM for SUM.

 

How to get key figures about the net process runtime and savings in your environment?

In the SUM directory under <DIR_PUT>/doc/analysis [applies for SUM 2.0; in case of SUM 1.0 the file is stored in <DIR_PUT>/htdoc] you will find the log file UPGANA.XML. When you copy this file and the UpgAnalysis.xsl file in a local directory and call the XML file you see it directly in a browser window.

When you run the SUM with nZDM on a test system at first you can use the figures to forecast your next run in production environment.

 

How to verify the needed database disc space?

As mentioned, the needed additional database disc space is minimized due to the focus on update/upgrade relevant tables for the copy to shadow operation. In order to calculate the needed DB disc-space you can use the experiences made in the first run. 

In SUM directory under <DIR_PUT>/var [applies for SUM 2.0; in case of SUM 1.0 the file is stored in <DIR_PUT>/bin] you find the log file “ALLTABU.DAT”, which shows the tables used by the R3trans. Besides of AIMs and conversions this table shows most of the table names part of the nZDM change recording.

Large tables (e.g. with size of 50 GB or more) can be identified with the help of the database analysis transaction in the Suite System (transaction DB02).

 

How to avoid long runtime of copy to shadow due to tables STXH and STXL?

In the previous SPs of SUM 1.0, when nZDM capabilities were delivered only on request, it was possible to get long copy to shadow runtime in pre-processing phase due to the STXH and STXLtables . Both tables are excluded from the shadow update with SUM 1.0 SP7.

Since the shipment of SUM 1.0 SP8 the copy to shadow is mainly taken over by a new technique "fast data copy". Issues regarding long running copy to shadow might be solved with this new technique finally.

 

Dumps in shadow system: PXA_NO_FREE_SPACE

If the parameter ABAP/buffersize is too small you'll get short dymps during the transfer process in the shadow. We recommend to extend the ABAP/buffersize to 800.000. (Trans.: RZ10)

See SAP Note 1678564 - Restrictions, Database-specific Settings, and Troubleshooting of nZDM for SUM, section 6 (Troubleshooting).


Why tables are not copied to the shadow?

The following exception have to be considered:

  • Cluster tables
  • Pool tables
  • G tables
  • Tables with large names (16 characters with secondery indexes with 3 Letters)
  • Index of tables

Big tables might be excluded from shadow operation due to a SAPup parameters:

With the parameter set_max_tab_size = ON this feature is activated (default value). You have the option to adapt the maximum table size of nZDM tables using the SAPup parameter isu_max_tab_size.


Adapt the value of this parameter in the SAPup_add.par file according to the following pattern.

  • SUM 1.0 and SUM 2.0 <= SP04: isu_max_tab_size = 100000000 (The value is specified in kilobytes, this example sets the maximum table size to 100GB [default: 50000000])
  • SUM 2.0 SP05 and higher: 
    • Be careful: with SUM 2.0 SP05, the value is now specified in MB, no longer in KB!
    • isu_max_tab_size = 100000 (The value is specified in megabytes, this example sets the maximum table size to 100GB [default: 50000])

See also SAP Note 1678564 - Restrictions, Database-specific Settings, and Troubleshooting of nZDM for SUM

How can the Impact Analysis for nZDM be activated?

With SUM 2.0 a new tool called Impact Analysis is available also for nZDM. With the Impact Analysis for nZDM you can get the answer for the following key figures:

  • Additional daily DB growth due to change recording
  • Database triggers might have to be removed from certain tables
  • Additional DB space requirements due to table cloning

SAP Note 2476860 describes the steps to enable the Impact Analysis for nZDM. One of the prerequisites is the export of statistical data. The export report is provided via SAP Note 2402270. Make sure that the SAP Note 2187612 is implemented in your production system before starting collecting the table statistics. For additional information on the tool Impact Analysis, see SAP Community blog "Impact Analysis as part of Software Update Manager 2.0".


How to include or exclude tables from the data transfer?

If you need to include or to exclude single tables into or from the data transfer, proceed as follows:

  • In the <DIR_PUT>/control [applies for SUM 2.0; in case of SUM 1.0 the file is stored in <DIR_PUT>/bin] subdirectory of the SUM directory, open the template file CRRTABLIST.LST.
  • To include a single table, add the following entry to the existing entries of the CRRTABLIST.LST template file using the following format: I <Tabname>
  • To exclude a single table, add the following entry to the existing entries of the CRRTABLIST.LST template file using the following format: E <Tabname>

Note that the format includes a space between the character and <Tabname>.

The best time to include or to exclude tables is after you have extracted the SUM package but before you start the upgrade since the CRRTABLIST.LST template file is processed in phase MODFILE_CRRTABLIST. After this phase, you can no longer include or exclude tables.