Key takeaways:

1. Selective Data Transition (SDT) offers a flexible middle ground between Brownfield and Greenfield migrations, combining selective data migration with system modernization. It comes in two main variations: shell conversion (bringing over most configurations selectively) and mix-and-match (starting fresh but integrating essential elements from ECC).
2. Choosing the right migration approach depends on several factors like the desired speed, level of process transformation, clean-core adoption, data migration scope, and go-live strategy (big bang vs. phased rollout). SDT is particularly attractive for companies needing to preserve important historical data and custom processes while still cleaning up and optimizing their systems.
3. Strong governance and planning are vital for SDT success. Because SDT involves multiple stakeholder groups and a complex data migration at the database level, clear project management, a stable scope, and multiple mock cutovers are essential to minimize business disruption and ensure a smooth go-live.

Choosing the right SAP S/4HANA migration path: Brownfield, Greenfield, or Selective Data Transition?

As SAP ECC customers prepare for the transition to S/4HANA, they are faced with a crucial decision: which migration approach best suits their business needs? Broadly, there are three main transition paths: Brownfield, Greenfield, and Selective Data Transition. Each approach comes with distinct benefits and trade-offs, making it essential to understand their key differences before choosing the best fit.

On one end of the spectrum is the Brownfield approach, also known as system conversion. This involves taking the existing ECC system and converting it as-is to S/4HANA. At the other extreme is the Greenfield approach, which entails a completely new implementation of S/4HANA. This approach allows organizations to start from scratch, redefining business processes, implementing new configurations, and adopting SAP best practices. What’s left in the middle is the Selective Data Transition approach – basically a hybrid of the Greenfield and Brownfield approaches.

Selective Data Transition: The hybrid approach with two key variations

Selective Data Transition (SDT) combines elements of both Greenfield and Brownfield. It allows businesses to retain critical processes and data while optimizing and modernizing their system.

Within SDT, there are two key variations:

• Shell conversion: This approach creates a “shell” of the existing ECC system, bringing over configurations while allowing for selective process and data migration. It provides an opportunity to eliminate obsolete custom code and streamline operations. Customers choose this option when they want to bring over most existing processes and configurations from ECC to S/4HANA, but still need to change certain processes and select specific data for the migration.
• Mix-and-match: This scenario starts with a new S/4HANA system (similar to Greenfield) but selectively integrates certain ECC processes and configurations. This approach enables businesses to retain essential elements while still leveraging SAP’s latest innovations. Customers choose this option when they prefer a new S/4HANA implementation, but still would like to bring over some of the processes and configurations from ECC.

Greenfield, Brownfield or Selective? Key factors in choosing the right approach

Several factors influence which transition path is most suitable:

Speed of transition
System conversion (Brownfield) is typically the fastest approach. Shell conversion also offers a fast transition, although the decision-making process on which configurations to carry over may slow down the overall timeline. In a mix-and-match scenario, the transition begins with a Greenfield setup, but critical processes and configurations from ECC can be selectively integrated. Identifying and incorporating the necessary processes into the new system requires additional effort, making the transition speed moderate to low. A completely new implementation generally has the slowest transition speed.

Clean-core adoption
Brownfield conversions tend to carry over legacy modifications, therefore clean core adoption is low. The shell conversion approach provides the opportunity to identify and remove obsolete custom code from the system, which makes the potential for clean core adoption relatively higher. Greenfield and mix-and-match approaches offer the best opportunity for a streamlined, clean-core system.

Process transformation
Brownfield keeps existing processes largely intact, while SDT and Greenfield enable varying degrees of business process redesign.

Data scope
In a Greenfield scenario, only essential data – typically master data and open transactions – is migrated to the new system. Brownfield migrations include the full transfer of historical and transactional data. The shell conversion and mix-and-match approaches support selective data migration, allowing organizations to decide which data is relevant to bring over. The scope of historical data migration can be further drilled down based on modules, objects, purchase orders, etc.

Go-live strategy
Brownfield requires a big bang cutover, whereas SDT and Greenfield allow for a phased rollout, reducing risk and disruption.

Big bang vs. wave-based (phased) approach

Once the customer decides on the overall approach, it’s equally important to choose the right go-live strategy. In general, the big bang approach is recommended as it reduces the complexity of managing parallel systems and allows for a faster migration. However, in some cases, migrating everything in a single weekend simply isn’t feasible. This could be due to the size of the database, the number of users, the complexity of interfaces, or other technical limitations.

In such scenarios, a wave-based approach may be more appropriate. This strategy divides the migration into smaller, manageable phases, reducing the immediate impact on the business. However, it is more complex because it requires careful planning to manage data consistency across systems, coordinate between multiple go-lives, and ensure that both legacy and new systems can operate in parallel without disruptions. While wave-based migrations demand more effort, they offer greater flexibility for organizations with highly integrated or large-scale environments.

Managing historical data during a migration

When considering a move to SAP S/4HANA, the decision to include historical data is a crucial factor in determining whether the Selective Data Transition (SDT) approach is the right fit. While a new implementation may be suitable when only master data and open items are required, many organizations choose the Selective Data Transition approach because they rely on existing customizations and critical business processes that they want to preserve.

SDT makes it possible to selectively migrate historical data – whether by time range (e.g. last one or two years), active company codes, or even down to specific objects – giving customers fine-grained control over what data is transferred. Unlike a system conversion, SDT works at the database level, enabling high-volume data migrations with minimal downtime. This means transaction data, such as purchase orders, can be carried over exactly as it existed in the source system. Importantly, there’s no need to archive all historical data in advance – only the required data is selected and migrated.

Archiving remains relevant for compliance-heavy industries like aerospace or pharmaceuticals, but SDT provides the flexibility to bring over just the right amount of history without the overhead of full pre-archiving.

Governance, scope, and teamwork: The foundations of a successful SDT project

Strong and consistent project governance is one of the most important success factors in a Selective Data Transition (SDT) project. Unlike system conversions, which are typically led by IT teams, SDT involves a broader range of stakeholders. In addition to IT and Basis teams, business users, functional experts, and shared service centers all play a crucial role. These teams are often distributed across different locations, making clear communication and alignment essential.

A well-defined and stable scope is critical. Changing the scope during testing can lead to confusion, delays, and reworking. That’s why it’s important to define the scope early, stick to it, and ensure that all data filtering, transformation, and validation activities are aligned with it.

Equally important is having a dedicated project team on both the customer and service provider sides. This should include a project manager, IT architect, and business owners for each key area. Change management also plays a big role in project success – mid-project upgrades, new rollouts, or added functionalities should be carefully reviewed and ideally avoided.

With clear governance, a committed team, and a stable scope, SDT projects have a much greater chance of success.

Planning for downtime in Selective Data Transition projects

The SDT approach typically requires a full shutdown of the source ECC system during the cutover. This is because data is migrated at the table level, making it necessary to lock users, stop batch jobs, and disable interfaces to ensure a consistent and accurate data extraction.

A typical SDT go-live weekend begins with ramp-down activities on Friday afternoon: locking users, halting interfaces, and preparing systems. Data migration and validation take place on Saturday, followed by ramp-up activities and final testing on Sunday. The goal is always to return the system to the business by Monday morning – minimizing disruption to operations.

Rehearsals are a key success factor here. Mock cutovers allow teams to test and refine every detail of the process, from technical steps to stakeholder coordination. Performance tuning also plays a major role, as each phase of the downtime, from data extraction to validation, needs to be optimized for speed without sacrificing data quality.

With the right preparation, a full data migration can be completed over a single weekend – bringing the organization live on S/4HANA without extended interruptions to core business processes.

Finding the right fit for your SAP S/4HANA migration

Choosing the right approach for your SAP S/4HANA migration depends on various factors, including your organization’s goals, timelines, and existing system configurations. While the Greenfield and Brownfield approaches offer different advantages, Selective Data Transition provides the ideal middle ground, allowing businesses to retain key data and processes while modernizing their systems.

By considering key factors such as the project scope, data migration needs, and governance, businesses can make a more informed decision about which approach aligns best with their objectives. Whether opting for Selective Data Transition or another path, a thoughtful approach to migration can help ensure a smoother transition to SAP S/4HANA.

Watch our recorded webinar where industry experts discuss how to choose the best migration approach for your business. Gain valuable insights on best practices, key success factors, and practical tips for a smooth transition to SAP S/4HANA.

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