OstrellECC to S/4HANA: brownfield, greenfield or selective? A plain-English guide
The three main routes from SAP ECC to S/4HANA, what each one means for your data, your processes and your budget, and how to choose.
Ostrell Consulting ·
Every S/4HANA conversation starts with the same question: which route should we take? There are three main answers, and each one suits a different kind of organisation.
1. Brownfield: convert what you have
A brownfield move, also called a system conversion, takes your existing ECC system and converts it technically to S/4HANA. Your configuration, custom code and full transaction history come with you.
It suits you if your processes still fit the business, your custom code is under control, and you want the shortest path off ECC.
Watch out for carrying years of workarounds into a new platform. A conversion is only as clean as the system you start with, so custom code review and data clean-up still matter.
2. Greenfield: start again
A greenfield move is a new implementation. You design S/4HANA close to SAP standard, then migrate the master data and open items you need.
It suits you if your ECC system no longer reflects how you work, you have heavy customisation you want to retire, or you want to move to a cloud edition built around standard processes.
Watch out for the size of the change. Greenfield is a business transformation, not an IT upgrade, and it needs real time from your process owners.
3. Selective data transition: keep what matters
Selective data transition sits in between. You build a new S/4HANA system and move selected data across, for example certain company codes, a chosen amount of history, or specific processes. It is usually delivered with specialist tools and partners.
It suits you if you want a cleaner design in some areas but need to keep history, or you are merging, splitting or reorganising entities as part of the move.
Watch out for complexity. It needs careful scoping and experienced people on the data side.
How to choose
| Question | Leans brownfield | Leans greenfield |
|---|---|---|
| Do your processes still fit? | Yes | No |
| How much custom code do you have? | Modest, well understood | Heavy, poorly documented |
| How much history must you keep online? | A lot | Little |
| Appetite for business change? | Low | High |
Most organisations don’t lack options. They lack a clear, fact-based view of which route fits them. That comes from looking at your actual system: custom code, simplification items, data quality and integrations.
Where RISE with SAP fits
RISE with SAP is a commercial and service bundle, not a technical route. You can reach S/4HANA through RISE on a brownfield, greenfield or selective path. Understand what RISE includes and what it leaves to you before you decide.
Our view
Start with a short readiness assessment. It gives you the facts to choose a route, a realistic timeline and a budget your board can stand behind. Book a clarity call and we’ll tell you honestly where we’d start.
