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The Sign-Off Table

Lesson 2 of 5

Archiving, retention and legacy access

13 min

Once you decide that data will be retained but not migrated, you have to decide where it will live and for how long. That plan must survive the shutdown of the old system. Many programs remember to plan the go-live and forget to plan the legacy system's end of life, then pay for an unused legacy system for years because nobody can prove it is safe to turn off.

Retention requirements come from outside IT

Retention periods are set by tax law, commercial law, product liability, contracts, industry rules and pending litigation. They differ by country, by data category and sometimes by company. They are not something the migration team should guess. For Alternadores del Norte's data, Contoso's legal and tax advisers in Mexico and the US produced a retention schedule listing each data category with its period, the event that starts the clock and the owner. Any legal hold (data that must be kept because of litigation or investigation) overrides the schedule until it is released.

Options for retained data

OptionHow it worksStrengthsWeaknesses
Keep the legacy system read-onlyThe legacy ERP stays up with users locked to display accessSimple; full context; familiar to usersOngoing cost, patching and security risk; a temporary answer
Data archiving in the sourceArchive objects write data to archive files; display through archive accessSAP standard; reduces database size; mature toolingNeeds the source system to read archives unless moved elsewhere
SAP Information Lifecycle Management (ILM)Rule-based retention management: archiving and destruction governed by retention rules, with legal holdsEnforces retention and destruction by policyRequires design and configuration effort
ILM retention warehouseLegacy data moved to a low-cost store so the source system can be decommissionedLegacy system can be shut down; data stays accessible for auditReporting is limited compared with the live system; needs planning early
Options for keeping retained data accessible after go-live. Many programs combine a read-only period with a decommissioning plan.
The Sign-Off Table · thesignofftable.com/academy/sap-dmg-401

SAP describes SAP ILM as managing the lifecycle of live and archived data based on rules, to cope with data protection and retention regulations. SAP positions three key scenarios: retention management (rule-based archiving and destruction of transactional documents), simplified blocking and deletion of personal master data, and the retention warehouse for decommissioning legacy systems. In classic data archiving, archive objects are run through Archive Administration (transaction SARA). Exact ILM features and licensing depend on your release and contract, so confirm them with SAP before you design around them.

A legacy end-of-life plan

  1. Go-liveLegacy ERP set to read-onlyUsers locked to display roles; interfaces off; batch jobs stopped
  2. Go-live + 1 to 12 monthsRead-only periodYear-end close, audits and returns use the legacy ERP for history
  3. After the first auditDecommissioning decisionRetention schedule checked; data moved to archive or retention store
  4. DecommissionLegacy ERP switched offAccess to retained data verified before shutdown
  5. End of retentionDestructionData destroyed per schedule, unless under legal hold
A typical legacy end-of-life plan. The durations are Contoso's choices for Alternadores del Norte's legacy ERP, not a standard.
The Sign-Off Table · thesignofftable.com/academy/sap-dmg-401

The first year after go-live is usually when history is needed most: the first year-end close, the first external audit on the new system, warranty claims and returns against old deliveries. Plan the read-only period to cover at least those events, then decommission deliberately rather than leaving the old system running indefinitely.

Prove retained data is usable

Retained data is only useful if people can find and read it. Before the legacy system is switched off, test the access path: can finance display a closed 2021 invoice with its line items? Can an auditor see the document's change history? Can a buyer find the purchase history for a supplier? These checks are as much part of the migration's acceptance as reconciling open items.

  1. Pick sample requestsTypical audit, tax, warranty and dispute requests, chosen with the owners
  2. Run them on retained dataThrough the planned access path, by the people who will use it
  3. Compare with the sourceResults match what the live legacy system showed
  4. Record evidenceSample, result, who checked, date
  5. Approve decommissioningOwners and internal audit sign before shutdown
Testing access to retained data before the legacy system is switched off.
The Sign-Off Table · thesignofftable.com/academy/sap-dmg-401

What would you do?

Eighteen months after company code 1910 went live, Contoso is still paying to run Alternadores del Norte's legacy ERP in read-only mode "just in case". What should the program recommend?

Key points
  • Retention periods come from legal, tax and compliance, not from IT; legal holds override them.
  • Options: read-only legacy, data archiving, SAP ILM retention management and the ILM retention warehouse.
  • Plan the legacy end of life: read-only period, decommissioning decision, shutdown, destruction.
  • Test access to retained data with real requests before switching the old system off.

Check your understanding · not graded

Lesson check

  1. 1. Who sets retention periods?

  2. 2. Which SAP ILM scenario supports decommissioning legacy systems?

  3. 3. What overrides a retention schedule until released?

  4. 4. What should happen before the legacy system is switched off?