SAP legacy decommissioning
Retiring a system is easy. Retiring it while the auditors, the tax authority and the business can still reach three decades of history is engineering.
When can you actually switch off ECC?
The honest answer: when nothing that still matters lives only there. That test has two halves. Operational data must be live in the successor system, reconciled and signed off. Historical data must be either migrated with evidence or retained somewhere that preserves access, meaning and auditability without the old application running underneath it.
Programmes stall on the second half. S/4HANA go-lives leave ECC running for years as an expensive read-only museum, because nobody separated the history question from the migration question early enough. The licence, infrastructure and skills bills keep arriving either way.
Historical data is not migrated data
Operational migration and historical retention are different disciplines. Operational data must transact in the new world, so it is transformed into the target model. Historical data must testify: who posted what, when, under which rules that applied at the time. Forcing decades of history through the operational migration inflates cost and often destroys evidential meaning in the process.
The retention route keeps history queryable and auditable outside the source application. Platform choices matter here, and this is where JiVS appears in architectures we design: purpose-built for carrying historical data and its business context after the application goes dark.
The one-way door
Decommissioning is one-way. After switch-off, every unanswered question about the data becomes permanent, which is why the evidence bar is higher than for an ordinary migration. When we retired a 30-year IBM Adabas mainframe for a multinational mining and energy group, every value was reconciled and audit-traceable before anyone touched the off switch. The result was zero post-load corrections, and a platform that could finally, safely, stop.
That is the standard we hold decommissioning to, because it is the standard the auditors hold you to, years after everyone who ran the old system has left.