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Depth 20.3 · Cloud, data and modernisation · Level 3

Legacy retirement

Legacy retirement is switching off an old system safely once something else does its job. For a period the replacement runs alongside the old system, and both are compared on the same work. The old one is switched off when the evidence shows nothing still depends on it, not when a date in a plan arrives.

Specification

Input
Access to the old system and its logs, the list of people and systems known to use it, and the replacement that will take over.
Method
We trace every user, report and connection that still touches the old system, run the replacement in parallel and compare results, then move users across in groups. Shutdown follows only when the logs show no remaining use.
Deliverable
A dependency register, parallel run reports, an archive of the data you must keep, and a shutdown record.
Measured by
Remaining dependencies in the register, differences found in parallel runs, and requests to the old system recorded in its logs.

Most often bought inPayments and fintech, Logistics and supply chain

The artefact, before and after

A dependency register, parallel run reports, an archive of the data you must keep, and a shutdown record.

Before: a blank legacy retirement record with a row for each of dependency tracing from logs and interviews, parallel running with result comparison, moving users across in groups, archiving data that must be kept, shutdown on evidence of no remaining use, and no entries. After: every row carries a finding and a checked status, which is the state the work hands over.

Inside it

  • 01Dependency tracing from logs and interviews
  • 02Parallel running with result comparison
  • 03Moving users across in groups
  • 04Archiving data that must be kept
  • 05Shutdown on evidence of no remaining use

Typical first engagement

The usual order of a first piece of work. Timing and price are set at scoping, once we have seen the stack.

  1. 01Usage evidenceYou get: Who and what still calls the legacy system, from logs rather than memory.
  2. 02Replacement planYou get: Where each remaining function and record will live.
  3. 03ShutdownYou get: Data archived, access removed and the system switched off with a record of each step.

Cloud, data and modernisation

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