Executing the ZDO-specific Phases and Activities

Objectives

After completing this lesson, you will be able to:

  • Identify the main blocks and important phases of ZDO
  • Monitor the rollover to the bridge subsystem
  • Perform the cut-over and rollback to the original subsystem

Main Blocks and Important Phases of ZDO

In the following section, the main blocks and important phases of ZDO are discussed. In addition to the phases of a standard update procedure, the following phases are specific for Zero Downtime Option. The details of each phase are described in separate lessons that are referenced in the following tables.

The figure, Important phases of ZDO, shows two different kind of phases:

  • ZDO specific dialog phases which require an active user interaction in SUM. These phases are numbered from A to E.
  • Phases that perform either check or preparation activities required to run ZDO. These phases are numbered from 1 to 10.

The following two tables describe each phase very briefly. Additionally, the technical phase name used by SUM is stated.

ZDO-specific Dialog Phases in SUM

LetterShort descriptionTechnical phase nameExplanation
ARoadmap selectionSELECT_ROADMAPSelect Zero Downtime Option as downtime-optimization approach in dialog Scenario Strategy.
BZDO specific parametersSUMASK_ZDO_CONFIGURATIONAsks if during the system restart (after phase REQ_USER_ROLLBACK_PREP), a system backup should be requested.
CApply shadow SAP NotesCHECK4NOTES_TOOL_SHD2Checks for SAP Note corrections required by SUM in the shadow system. These SAP Notes belong to the target release.
DRollover to bridgeREQ_USER_ROLLOVER_PREP

Completed with phase: REQ_USER_ROLLOVER_FINAL

After passing this phase, connected users will operate on the bridge subsystem.
ERollback to originalREQ_USER_ROLLBACK_PREP

If chosen in phase SUMASK_ZDO_CONFIGURATION that a backup has to be requested, you prompt in phase REQ_ZDO_SYSTEM_BACKUP to perform the complete system backup

Completed with phase: REQ_USER_ROLLBACK_FINAL

This phase indicates that the upgrade related activities are completed. When continuing, the bridge subsystem will be stopped and the original system will be restarted on the target release.

Further ZDO specific phases in SUM

NumberShort descriptionTechnical phase nameExplanation
1BW usage checkRUN_RSPTBFIL_ZDM_CHECK_BWChecks for active usage of SAP Business Warehouse configuration in the system.
2ZDO DDIC consistency checkPARRUN_ZDO_CONSISTENCY_*The purpose of the check is to find inconsistencies well in advance already on the original system as part of the module General Checks.
3Test importGENKEYTRACEPreparation step required for ZDO table classification. The test import calls R3trans to trace the content that will be later imported in phase TABIM_UPG.
4Table classificationRUN_RSPTBFIL_ZDM_CLASSIFYIn this phase, tables are classified according to how they are handled during the upgrade.
5Impact AnalysisRUN_IMPACT_ANALYSIS_ZDOAnalysis of the impact of table classification to productive usage statistics for tables changed by after import methods. As of this phase, the dialog version of Impact Analysis can be used as well.
6Preparation of bridge subsystemVarious phasesAll relevant artifacts and objects needed to run the bridge subsystem will be generated right before the rollover to bridge happens.
7Smart switchEU_SWITCH_ZDMThis phase renames all tables classified as clone or clone read-only.
8Initial table copySQLRUNTASK_FDCT_TRANSFERThis phase creates a clone for the target version of all tables classified as clone or clone read-only.
9Replay changesRUN_ZDOREPLAY_REPLAY_LKPMThe CRR (Change Record and Replay) framework is used by ZDO. While copying the clone tables, changes will be captures that will be replayed by this phase.
10Illegal table access checkRUN_CHECK_ILLACCESSChecks for illegal table access from the upgrade subsystem.

Rollover to the Bridge Subsystem

One important step during the Zero Downtime Option (ZDO) execution is the smooth transition to the bridge subsystem. This section provides details on the transition phase.

The transition of the users to the bridge subsystem in phase MAIN_BRITRANS/REQ_USER_ROLLOVER_PREP starts and rolls all users and work processes over to the bridge subsystem. This process happens seamlessly in the background using the reconnect feature built-in of the SAP Kernel.

The right timing for the rollover should be chosen individually. More information on this can be found in section Planning Aspects of a ZDO Maintenance Project in unit 3.

Monitor the Rollover to the Bridge Subsystem

Select Start Exercise to start the simulation.

Steps

  1. Prepare the rollover to the bridge subsystem.

    1. SUM reached the phase REQ_USER_ROLLOVER_PREP.

    2. To start the rollover, choose Next.

    3. Various phases are now executed. The phase BRIDGE_RECONNECT reconnects all work processes (disp+work) to the bridge database schema.

  2. Log on to the sandbox system that is currently being upgraded using ZDO.

    1. Log on to the system with user DDIC_DEV. The password is already pre-filled.

  3. Monitor the rollover to the bridge subsystem using the ABAP report, DBCONINFO.

    1. In the transaction box, enter transaction code SE38.

    2. Type in the report name, DBCONINFO.

    3. Either press F8 (on your keyboard) or use the execute button to run the report.

    4. Select the display option Display as ALV grid and select the execute button.

    5. Check the output in the ALV grid. In particular, the column DBUser shows that the active work processes have been reconnected already to the bridge database schema.

  4. Monitor the rollover using the work process overview.

    1. Enter transaction code SM50 in the transaction box.

    2. Check if there are any processes that are not yet reconnected. These processes would be highlighted in yellow.

  5. Check the active batch jobs in the system.

    1. The job overview transaction SM37 is launched automatically as part of the exercise.

    2. Choose the Execute button in the entry screen of transaction SM37.

    3. Check the result list of active batch jobs. All batch jobs are still active and successfully connected to the bridge database schema.

  6. Switch back to the SUM UI and resume the ZDO upgrade procedure.

    1. All users and background processes are successfully reconnected to the bridge subsystem.

    2. To resume the SUM procedure, choose Next.

Cutover and Rollback to the Original System

This section covers the rollback from the bridge to the original system during a Zero Downtime Option (ZDO) maintenance event.

For details, see section Backup and Recovery Strategy in unit 3.

Execute the Rollback to the Original Subsystem

Select Start Exercise to start the simulation.

Steps

  1. Prepare the rollback to the original subsystem.

    1. SUM reached the phase REQ_USER_ROLLBACK_PREP.

    2. Check the dialog screen in SUM.

  2. Log on to the sandbox system that is currently being upgraded using ZDO to check the source release.

    1. Log on to the system with user DDIC_DEV. The password is pre-filled.

    2. Open the system status information by choosing MoreSystemStatus...

    3. Choose the lens icon next to the product version to show the details on the installed software.

    4. Check the table for the version installed for SAP S/4HANA. The system currently runs in SAP S/4HANA 2020 SPS 00 which is based on SAP_BASIS 755.

    5. Close the dialog by confirming it.

  3. Resume SUM and start the rollback to the original subsystem.

    1. Choose Next to start the cut-over and rollback.

    2. Monitor the rollback procedure. The phase STOP_BRI stops the bridge subsystem.

    3. During the Configuration milestone of SUM, in phase SUMASK_ZDO_CONFIGURATION, the check box "Yes, request the backup" was selected. Hence, this phase REQ_ZDO_SYSTEM_BACKUP asks now to perform a complete system backup. Check the dialog.

    4. Choose Next to resume the SUM procedure.

    5. The original subsystem running on the target release is started in phase STARTSAP_ORIG.

    6. When phase REQ_USER_ROLLBACK_FINAL is reached, the rollover is completed.

  4. Log on to the sandbox system to check the target release.

    1. The log on has been performed automatically in this part of the exercise.

    2. Open the system status information by clicking on MoreSystemStatus...

    3. Choose the lens icon next to the product version to show the details on the installed software.

    4. Check the table for the version installed for SAP S/4HANA. The system runs now on SAP S/4HANA 2020 FPS 02 which is based on SAP_BASIS 755.

    5. Close the dialog by confirming it.

  5. Execute the remaining phases of the SUM procedure.

    1. SUM is waiting in the dialog phase REQ_USER_ROLLBACK_FINAL.

    2. Choose Next to resume the SUM procedure.

    3. SUM waits again in phase REQ_FINISH_IMPORT.

      Note
      After the phase REQ_FINISH_IMPORT, you must not import transports in parallel to SUM. Make sure that all imports of transports have been finished. Alternatively, you can import the transport at this point while SUM waits in this phase. Once all transport imports are completed, resume SUM. If SUM reached the EXIT dialog, the import of transports is also possible again.
    4. Select the check box "I confirm that no more imports are running."

    5. Choose Next to resume the SUM procedure.

    6. In the feedback form, select the type Development system.

      Note
      Always submit the feedback as this helps SAP to improve the upgrade procedure and runtimes of the upgrade. It also enables you to leverage the Technical Downtime Optimization application. The app is part of SAP ONE Support Launchpad. For details, see SAP Note 2881515.
    7. Scroll down and click the Send button.

    8. Choose the Close button to confirm the dialog.

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