S/4HANA Public vs. Private Cloud — What ECC Customers Should Be Doing Now

Every SAP ECC customer eventually reaches the same crossroads: When do we move to S/4HANA, and how do we choose between Public Cloud and Private Cloud?

For many organizations, that decision point still feels years away — late 2027, early 2028, or even beyond. But here’s the truth every industry expert knows: the organizations that thrive in S/4HANA are the ones that start preparing long before the project officially begins.

This fourth installment in our S/4HANA Public vs. Private Cloud series focuses on exactly that — the practical, high‑value steps ECC customers should be taking today to ensure a smooth, informed, and strategically aligned migration tomorrow.

Before we dive in, here are the earlier articles in the series for context:

• S/4HANA Public vs. Private Cloud — Understanding the Fundamentals 

• S/4HANA Public vs. Private Cloud — Understanding the True Cost Picture

• S/4HANA Public vs. Private Cloud — Customization Isn’t Dead—It Just Grew Up 

Now let’s explore what ECC customers should be doing right now — even if their migration is still a year or two away.

SAP Digital Discovery Assessment (DDA)

The Digital Discovery Assessment is SAP’s no‑cost, collaborative evaluation platform used during the Discover phase of SAP Activate. Think of it as the “front door” to your S/4HANA journey — a structured way for decision makers and partners to evaluate fit, scope, and deployment options.

How it works: DDA is split into two parts:

• Quick Qualification — identifies whether Public Cloud or Private Cloud is the best fit

• Detailed Discovery — captures business processes, integrations, countries, scope, and produces a formal handover document for implementation teams

It can also incorporate insights from Signavio Process Insights, making it even more powerful.

Why it matters: DDA helps organizations avoid blind spots early. It clarifies whether your business model aligns with Public Cloud standardization or whether Private Cloud flexibility is required.

Cost & value: DDA is free — and the value comes from clarity. It prevents misalignment, scope creep, and costly surprises later.

SAP Signavio Process Insights

If DDA is the front door, Signavio Process Insights is the flashlight that reveals what’s actually happening inside your ECC system.

How it works: Signavio analyzes real operational data from your ECC system and delivers insights within a week. It identifies process variants, bottlenecks, inefficiencies, and opportunities for automation or standardization.

What it delivers:

• Actual process performance metrics

• Root cause analysis

• Recommendations by line of business

• Fit‑to‑standard readiness

• Guidance on Fiori apps and S/4HANA capabilities

Why it matters: Public Cloud thrives on standardization. Signavio shows whether your organization is ready for it — or whether Private Cloud’s flexibility is a better match.

Cost & value: The discovery version is free. The value comes from data‑driven decision making and a stronger business case for S/4HANA.

SAP Readiness Check

Readiness Check is the technical backbone of S/4HANA preparation. It evaluates your ECC system across dozens of dimensions and highlights what must change before migration.

What it covers:

• System & landscape requirements

• Add‑on compatibility

• Simplification items

• Custom code impact

• HANA sizing

• Data volume reduction opportunities

• Integration inventory

• Financial data quality

• Recommended Fiori apps

• Customer Vendor Integration (CVI) readiness

• Planned downtime simulation

Why it matters: Readiness Check reveals the technical realities of your migration. It shows whether your system is ready for Public Cloud guardrails or whether Private Cloud’s compatibility is required.

Cost & value: Readiness Check is free. The value comes from eliminating uncertainty and enabling accurate planning.

SAP STAR Report (Trusted Authorization Review)

Licensing is one of the most misunderstood aspects of S/4HANA. The STAR Report removes the guesswork.

How it works: SAP analyzes your existing ECC authorizations and maps them to S/4HANA user license types (Advanced, Core, Self‑Service). It simulates future usage based on actual system data.

Why it matters: This report prevents over‑licensing, under‑licensing, and negotiation surprises. It is especially important for Public Cloud, where user types directly impact subscription cost.

Cost & value: STAR is an SAP‑delivered service. The value comes from clarity before entering licensing discussions.

Integration & Third‑Party System Documentation

Every ECC system is surrounded by a constellation of integrations — banking, EDI, e‑commerce, reporting, 3PL, custom interfaces, and more.

Why it matters: Public Cloud often requires rebuilding legacy interfaces to meet clean‑core and integration guardrails. Private Cloud allows more reuse. Without a complete inventory, organizations underestimate effort, cost, and timeline.

Cost & value: This work requires internal effort or partner support. The value comes from preventing integration surprises during migration.

Custom Code Assessment (ATC & Custom Code Migration Worklist)

Custom code is often the single largest technical variable in an S/4HANA migration.

How it works: Tools like ATC and the Custom Code Migration Worklist identify:

• What custom code is compatible

• What must be remediated

• What should be rebuilt

• What can be retired

Why it matters: Public Cloud enforces clean‑core principles. Private Cloud allows classic extensibility. Understanding your custom code footprint is essential to choosing the right deployment model.

Cost & value: This assessment requires effort but pays off by reducing remediation cost and preventing surprises.

SAP Customer Evolution Kit

This free SAP tool helps organizations understand how S/4HANA can transform their business.

What it provides:

• Transformation roadmap guidance

• Value realization scenarios

• Industry‑specific insights

• Capability mapping

Why it matters: It helps organizations shift from “technical upgrade” thinking to “business transformation” thinking — a critical mindset shift for Public Cloud adoption.

Cost & value: It’s free. The value comes from strategic alignment and executive buy‑in.

Summary

ECC customers don’t need to wait until 2027 or 2028 to begin preparing for S/4HANA. The smartest organizations are already running readiness checks, analyzing processes, documenting integrations, evaluating custom code, and using SAP’s free tools to build clarity and confidence.

These steps don’t commit you to Public Cloud or Private Cloud — they simply ensure that when the time comes, you’ll make the right decision with full visibility and zero surprises.

Final Thoughts

If your organization is evaluating its S/4HANA strategy and wants expert guidance, CONTAX is here to help. Visit www.contax.com or contact info@contax.com to start the conversation.