SAP ILM for S/4HANA Migration: Retaining Legacy Data Without the Legacy Systems

Dear friends,

I was chatting with a CIO last month about their S/4HANA migration, and they said something that stuck with me: “We’ve spent two years planning the technical conversion, but nobody can tell me what to do with 15 years of ECC data.”

I get it. When you’re staring down a migration deadline, the question of what happens to legacy data feels like tomorrow’s problem. But here’s the thing — that question has a way of becoming today’s crisis when you realize you can’t just delete everything, but you also can’t afford to keep two SAP landscapes running forever.

Whether you’re managing a greenfield S/4HANA implementation, a brownfield system conversion, or a selective data transition, you’re going to face the same challenge: what to do with historical data when you want to shut down legacy systems.

Today, I’d like to share what I’m seeing on the ground — how organizations are using SAP Information Lifecycle Management (ILM) to solve this problem, and why it’s worth thinking about now rather than after your go-live.

Why This Conversation Is Happening Now

SAP has announced the end of mainstream maintenance for SAP ECC in 2027, with extended support available until 2030 at additional cost.

This deadline has triggered one of the largest ERP migrations in enterprise IT history. Thousands of organizations are planning their move to SAP S/4HANA, and many are discovering that the hardest question is not the migration itself — it’s what to do with decades of historical data.

Most ECC systems contain 10–20 years of transactional records, much of which must be retained for audit, tax, or regulatory reasons. Migrating all of that data into S/4HANA can dramatically increase database size, extend migration timelines, and inflate HANA infrastructure costs.

This is why data lifecycle management — especially archiving and system decommissioning strategies — has become a critical workstream in S/4HANA programs.

Organizations that address it early often achieve:

• smaller migration scope
• faster conversion timelines
• lower HANA infrastructure requirements
• cleaner retirement of legacy systems

Those that postpone it frequently discover they’re running two ERP landscapes in parallel for years.

What is SAP ILM?

SAP ILM — Information Lifecycle Management — is SAP’s built-in framework for managing data from the moment it’s created through archiving to final deletion.

I know, I know. That sounds like one of those SAP modules that sits in the back of the system and never gets discussed in executive briefings. But here’s why it matters:

SAP ILM does three things that directly impact your migration:

1. Data Archiving — Moves historical data out of your production database. Smaller database, better performance, lower HANA memory costs. (Many organizations see 20–50% reduction with strategic archiving, according to SAP Data Volume Management guidance.)

2. Retention Management — Applies rules for how long data must be kept based on legal and business requirements. This isn’t just “keep it for 7 years” — it’s about knowing exactly when to block personal data from processing (hello, GDPR), when legal holds apply, and when destruction is finally permitted.

3. Retention Warehouse — This is the one that surprises people. ILM can archive large portions of historical business data into a compliant repository. Then you shut down the old system while maintaining full audit access.

That third capability? That’s where the real savings live.

The Problem Most Teams Discover Too Late

Let me paint a picture I’m seeing repeatedly in Canadian public sector organizations:

You’ve been running SAP ECC since 2010. Your database has grown to a few terabytes. Most of that data is transactional history from 2010-2015 that nobody touches — except when audit asks about a payment from 2012, or legal needs contract records, or the tax authority wants to see historical GL balances.

You can’t delete it. But you also can’t keep paying six figures annually to maintain an aging ECC landscape just to store data you access maybe 2% of the time.

When S/4HANA migration comes, you have three choices:

Option 1: Bring everything forward. — Massive database, high HANA licensing costs, longer conversion windows. I’ve seen teams spend months just trying to figure out how to migrate terabytes of historical data that nobody really needs in daily operations.

Option 2: Delete aggressively. — Risk non-compliance, legal exposure, operational gaps. The organizations that try this usually end up keeping more than they planned because nobody wants to be the person who deleted something important.

Option 3: Archive with ILM. — Keep compliant access to historical data, reduce production footprint significantly, decommission legacy systems. This is what ILM makes possible, and frankly, it’s the approach more teams should be considering from day one.

How ILM Works for Different Migration Paths

There are three main approaches to S/4HANA migration, and ILM plays a different role in each. I want to walk through them clearly.

System Conversion (Brownfield)

This is a technical conversion of your existing ECC system to S/4HANA — think of it as renovating your house while living in it.

What comes with you: Most data and configuration convert to S/4HANA. Historical data stays unless you archive it first. Custom code must be remediated for S/4HANA compatibility (this is important — it’s not just “lift and shift”). Business processes generally stay the same, though some adjustments are required due to S/4HANA simplifications.

ILM role: Archive historical data before the conversion. When you shrink the ECC database before migration, you reduce what needs to be converted — shorter conversion windows, smaller HANA memory requirements, lower licensing costs, more stable process.

One organization I worked with reduced their ECC database by 40% through pre-migration archiving. Their brownfield conversion took half the time they had budgeted for, and their HANA licensing came in 30% under estimates. The archived data remained accessible through ILM — just not bloating the production system they were converting.

Risk profile: Primarily technical risk — you’re working with a known system, but conversion complexity depends on your custom code and data volume.

New Implementation (Greenfield)

This is a completely new S/4HANA implementation with redesigned business processes — think of building a new house from scratch.

What comes with you: Fresh configuration, rebuilt processes, only essential master data and recent transactions. Minimal historical data migrates. This is the cleanest slate but the longest journey.

ILM role: The Retention Warehouse becomes essential here. Since you’re not migrating historical data to S/4HANA, where does it go? ILM. You archive the historical data from your ECC system into the Retention Warehouse, migrate only current data to the new S/4HANA system, and decommission the old landscape entirely — while maintaining full audit trails and regulatory compliance.

In many organizations, the archived data is then stored in an application retirement platform such as OpenText InfoArchive, which provides long-term access to historical records after the legacy ERP system has been decommissioned.

I’ve seen organizations eliminate six-figure annual maintenance costs within months of go-live using this approach. The historical data sits in InfoArchive, accessible for audit and legal purposes, but the legacy system is gone.

Risk profile: Primarily organizational risk — business process change is significant, and user adoption can be challenging. But you end up with the cleanest system.

Selective Data Transition (SDT)

This is the middle ground — a new S/4HANA system where you selectively migrate business units, data, and configuration. Think of it as moving to a new house and only bringing the furniture you still need.

What comes with you: You choose — company codes, business units, recent years, clean master data. Configuration can be reused or redesigned. Custom code can be selectively migrated or rebuilt.

ILM role: Archive what you don’t bring. Historical data stays in ILM Retention Warehouse while current operations run in the new S/4HANA system. You get the benefits of a cleaner system without the full disruption of greenfield.

Many organizations then move that archived data to an application retirement platform like OpenText InfoArchive for long-term retention and access, completely separating it from the operational environment.

Risk profile: Primarily data transformation risk — the complexity is in selecting and migrating the right data correctly. But you can reduce technical debt while maintaining some continuity.

Which approach is right for you? It depends on your organization’s situation. Brownfield is usually the fastest implementation path, but technical complexity can still be significant depending on your custom code, add-ons, and data volume. Greenfield is longest with highest organizational change, but gives you the cleanest slate. SDT sits in the middle — more data transformation complexity, but can reduce technical debt while keeping some continuity.

A general guideline: Most organizations retain only 3–5 years of operational data in S/4HANA, while older historical data is archived for compliance. In many S/4HANA programs, more than 70–80% of historical data is never accessed operationally, making it a strong candidate for archiving rather than migration.

If you’re running 15 years of ECC data, you might only need to migrate the most recent 3–5 years — the rest goes to ILM Retention Warehouse for compliant access.

Either way, ILM gives you options beyond “migrate everything” or “delete and pray.”

The Compliance Reality

This matters more in Canadian public sector than many organizations realize.

If you’re subject to MFIPPA (Ontario municipal), FIPPA (provincial equivalents), or PIPEDA (federal privacy law), you need to demonstrate:

• Data is retained for required periods
• Personal data is blocked from processing when no longer necessary
• Deletion happens at the right time (not too early, not too late)
• Legal holds prevent destruction of evidence

SAP ILM provides the policy framework and audit trails to prove compliance. You configure retention rules per country, organizational unit, or data type, and ILM enforces them automatically.

For GDPR requirements like “right to be forgotten,” ILM can block personal data from processing while maintaining it for legal/audit purposes until deletion is permitted. The system knows the difference between “stop using this data” and “destroy this data” — which is exactly the nuance regulators expect.

The Business Case — Let’s Talk Numbers

Many organizations underestimate the cost of keeping legacy ERP systems online solely for historical access.

In some environments, companies maintain entire SAP landscapes simply so auditors can retrieve records from transactions that occurred a decade ago. The database is there, the application servers are running, the licenses are active — all to support occasional lookups of old data.

Application retirement platforms such as OpenText InfoArchive address this problem directly. They preserve historical data in a searchable archive while allowing the original system to be shut down entirely — eliminating infrastructure, database, and maintenance costs.

A medium-sized ECC landscape costs six figures annually to operate — infrastructure, licensing, maintenance, support staff. Large enterprises often have dozens of legacy systems from mergers and acquisitions, each carrying similar costs.

If you can decommission just one legacy system using ILM Retention Warehouse, the savings can fund a significant portion of your S/4HANA migration.

Add in HANA footprint reduction — archiving before brownfield conversion can significantly reduce database size, directly lowering HANA memory costs — plus risk reduction through documented retention policies and automated deletion, plus operational efficiency from smaller production databases.

The ROI is usually clear within 2-3 years. In some cases, I’ve seen it pay for itself in year one just from eliminated legacy system maintenance.

Where Application Archiving Platforms Fit In

SAP ILM provides the policy framework, but organizations often need a long-term repository for historical application data once legacy systems are retired.

This is where application archiving platforms come into play.

These platforms are designed specifically to retain structured business data from legacy systems while allowing organizations to safely decommission the original applications.

One example is OpenText InfoArchive, an application retirement platform designed to preserve historical data from systems such as SAP ECC while enabling secure, compliant access for audit, legal, and operational needs.

Instead of keeping entire ERP systems running simply to access old records, organizations can:

• Archive historical data into a centralized platform
• Decommission the legacy application
• Retain compliant access to records for decades

When combined with SAP ILM policies, platforms like InfoArchive allow organizations to separate operational ERP data from long-term historical records, reducing infrastructure costs while maintaining regulatory compliance.

Many organizations implement a layered approach:

This layered model helps enterprise architects understand how the pieces fit together.

One more thing: Application retirement platforms are particularly valuable for organizations running multiple legacy systems after mergers, acquisitions, or ERP upgrades. If you’ve inherited three different ERP landscapes and need to consolidate onto S/4HANA, you can archive all three into a single platform and shut down the old systems permanently.

Getting Started — A Practical Sequence

If you’re planning an S/4HANA migration and haven’t considered ILM yet, here’s what I’m recommending to the organizations I work with:

First, assess your legacy footprint. What data exists, what retention requirements apply, what systems can realistically be decommissioned after migration? You need this inventory before you can design an ILM strategy.

Second, define retention policies. Work with legal, tax, and records management to document requirements. This takes longer than you think — start early.

Third, pilot archiving. Start with high-volume objects like FI, SD, and MM to prove the approach and quantify benefits before scaling.

Fourth, plan the migration with ILM in mind. Factor archiving work into your project timeline and resource allocation. The archiving can happen months before technical migration, reducing pressure on the conversion window.

Fifth, implement Retention Warehouse for legacy decommissioning. For greenfield or SDT approaches, design the path to shut down old systems while maintaining compliant access.

Most organizations find that ILM projects work best as a parallel workstream to the main S/4HANA conversion. Don’t try to bolt this on at the end.

The Bottom Line

SAP ILM isn’t the headline feature of an S/4HANA migration. It doesn’t get the attention of new Fiori apps or HANA’s in-memory performance.

But it solves one of the most expensive, persistent problems in enterprise IT: what to do with legacy data when you want to shut down legacy systems.

I’m convinced that organizations planning for ILM early in their S/4HANA projects end up with smaller databases, lower costs, and cleaner decommissioning paths. The ones that don’t often find themselves still paying for legacy systems years after their “migration” is technically complete.

Either way, whether you’re just starting your S/4HANA planning or you’re deep in the technical details, I’d invite you to step back and ask: what’s our plan for the historical data?

If the answer is “we’ll figure it out later,” you might want to reconsider.

Keep building, Michael