Helping companies sustain their competitive edge and exponential growth are just two of the many benefits that SAP S/4HANA offers. It also provides numerous other benefits like innovation, ease of use, accurate forecasting, and faster analytical insights. To enjoy each of these benefits the transition to SAP S/4HANA must be planned optimally and reliably.

In SAP S/4HANA, downtime can be both planned and unplanned. Whichever it may be, system downtime can prove to be costly or impact businesses adversely. Less downtime will result in maximum advantages for businesses. However, enterprises cannot upgrade their current SAP S/4HANA systems or migrate to SAP S/4HANA with ZERO downtime. In this definitive guide, we will explore how you can reduce downtime in SAP S/4HANA upgrade projects.


Different Types of Downtime in Sap S/4HANA

The term “downtime” has numerous meanings. Business Users are unable to post any business transactions during downtime in the production system.

Technical DowntimeThe upgrading procedure is carried out during this time without the system being accessible to end users through the upgrade tools. It does not include the time required for data backup and final testing.
Business DowntimeThis represents the overall length of time the system is unavailable to users. It considers the time required for data backup, final testing, and technical outages.
Uptime DowntimeThe time that users may utilize the system’s apps in real-world settings while the update is underway.
Runtime DowntimeThe time needed to complete the upgrading procedure. It includes total upgrade uptime, technical downtime, and business downtime.


What are the Approaches for SAP S/4HANA Downtime Reduction?

One of the biggest concerns during technical or business downtime is that businesses cannot rely on their ERP platform. During this time, background activities and integration flows are halted. Even more so than financial and procurement processes, sales, warehouse, and production suffer. Thus, one of the primary objectives of the conversion project is to minimize business downtime during the weekend.

For conversion projects, a downtime reduction strategy or plan is crucial, since less downtime will result in maximum advantages for the businesses. Conversion projects’ downtime is greatly reduced with the use of downtime optimization. Users may cut down on S/4HANA conversion downtime by using the new Zero downtime technique. SAP offers the following solutions for minimizing downtime:

Standardnear Zero Downtime Maintenance (nZDM)Downtime Optimized DMO (DO-DMO)Downtime Optimized Conversion (DO-DMO Conversion)Near Zero Downtime Technology (NZDT)
Generally AvailableApplicable with Source DB as SAP HANAApplicable with Source DB not SAP HANARequires SAP Consultant with Advanced KnowledgeService Based. Requires tool license and consulting service
Normal ApproachMove table structure adaptations and content party in uptime for upgradeMigrate selected large tables party in uptimeMove migration and data conversion partly to uptimeHigh effort, specialized skills, and some business restrictions while NZDT triggers are active. Based on the clone approach


Important Differences between Downtime Optimization Approaches

Standard ApproachNear-Zero Downtime Maintenance Approach (nZDM)Zero Downtime Option (ZDO)
Numerous downtime optimization including shadow system operationsDowntime reduction by moving downtime-relevant phases to uptimeAll phases running during uptime
Normally available for all customersNormally available for all customersAvailable on request only for pilot customers


  1. Standard Approach for Downtime Minimization

The methods for minimizing downtime have changed dramatically during the past few years. Three basic methods for implementing release upgrades, support package stacks, and feature package stacks are included with Software Update Manager 2.0. The SUM tool often provides access to this. The technical downtime period is where lengthy SUM processes like data migration, software updates, and XPRAS AIMMRG / FI Conversion are now taking place.

Major enhancements have been made to both the standard and near-Zero Downtime Maintenance (nZDM) to reduce technical downtime. The usual technique, as well as nZDM, cannot, however, decrease technical downtime. As the next step of downtime optimization, the Zero Downtime Option (ZDO) of SUM can be used to accomplish this. But keep in mind that the more you put into the project, the more you want to minimize downtime. The work comprises both project planning effort and testing effort, with zero downtime updates requiring more testing.


  1. Zero Downtime Option (ZDO) Approach for Downtime Minimization

The zero Downtime Option (ZDO) is another efficient approach for SAP S/4HANA downtime minimization. It allows you to apply feature and support package stack updates without technical downtime. With ZDO, you can significantly reduce the overall business downtime. During implementation, the approach requires additional effort for project planning, impact analysis, and test runs.

Basic Steps of the ZDO Approach

  • Business users utilize release 1, the source release, to operate the original system.
  • The SUM uptime processing begins in the interim.
  • SUM will easily transition end users to the bridge subsystem, which still reflects the source release, after uptime processing.
  • The target release is completed concurrently by SUM as the business continues to operate.
  • Transactional consistency is preserved throughout the maintenance operation.
  • The target release has to be triggered after the maintenance event.
  • The following stages are part of the cut-over and activation of the target release: Ramp-down release 1, parallelized restart of all application servers by SUM, and Ramp-up of release 2.
  • Users will begin working on release 2, which serves as the target release when the system has been restarted and ramped up.


  1. Near ZERO Downtime Technology Approach for Downtime Minimization

By employing a dedicated HW for the clone system, triggers for the installation of the source, DMIS add-on installs, and delta replay of data processing, SUM stages are completed in uptime on a cloned NZDT. This reduces the total business downtime. Note that no post-processing procedures, such as reconciliation and validation, may be optimized for downtime.

How does SAP NZDT work?

We can significantly reduce downtime for an SAP S/4HANA conversion using the Near Zero Downtime (NZDT) approach. The project-based solution makes use of the SAP DMIS add-on. It necessitates consulting assistance.

Technical and Hardware Requirements

NZDT downtime minimization approach requires near about 200GB of additional DB Space. It is essential for DMIS SP15, logging tables, NZDT notes, users, and authorizations. It also requires:

  • 50%–60% compute and 100% DB Size of Clone Server.
  • APP, MWB (migration workbench), and DB (64GB RAM, 16 core CPU, 500GB DB Storage). The Source, Clone, and Target Connections in DBCO.
  • Run-at-source App Server for DMO (128GB RAM, 32 Core CPU, 2.5 TB Storage).
  • Data Center to AWS Network Bandwidth (5Gbps to 10Gbps),
  • Deployment of MCOD. The Proxy schema would be erased upon data replay.
  • Run-at-target App Server for DMO (128GB RAM, 32 Core CPU, 2.5 TB Storage).

Steps to Minimize the Downtime

  1. Make a clone of the productive system.
  2. Carry out migration on the clone system.
  3. Resynchronized the productive system and the clone. The new productive system is the clone system.

Stages for Migrating to SAP S/4HANA

  1. Recording over DB-Triggers
  2. System Isolation and Cloning
  3. SAP S/4HANA Upgrade or Installation
  4. SAP S/4HANA Migration
  5. Online delta replay
  6. Downtime
  7. Offline Delta Replay
  8. SAP S/4HANA Migration of Delta
  9. Last Transports
  10. System Switch/Infrastructure Change
  11. Final Validation

Final Takeaways,

Minimizing downtime is crucial to the planning and execution of SAP S/4HANA update initiatives. As vital as the objective is, it can get challenging for both large and small & medium-sized enterprises. It is because there are expenses and consequences of system downtime that businesses must face. For upgrades and conversion projects, less downtime will result in maximum advantages for businesses.

At Techatalyst, we help and guide you to make the most of it. We help you with assessment, preparation for conversion, pre-conversion, conversion, post-conversion, and application testing.


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