Lesson 3 of 5
Dual tracks: project and maintenance
11 min
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Production does not stop changing while a project runs. Fixes, legal changes and small enhancements keep arriving. If the project builds in the same development system that feeds production, half-finished project work can block urgent fixes, or slip into production with them. A dual track landscape separates the two: a maintenance line that mirrors production and carries fixes, and a project line where the new release is built. The price is double maintenance, usually called retrofit: every fix made in the maintenance line must also be made in the project line, or it is lost when the project goes live.
Contoso's dual track during the conversion
During the conversion, Contoso's dual track was built in. ECC production EP1 kept running, supported through ED1 and EQ1 with ChaRM on SAP Solution Manager 7.2. The SAP S/4HANA project ran in CMD and CMQ, managed in SAP Cloud ALM. SAP's guidance for converting a three-system landscape fits this pattern: convert a sandbox copy of production first, then a duplicate of development, then a duplicate of quality, then rehearse on a production copy and finally convert production, keeping the gap between the development and production conversions short so dual maintenance does not drag on.
- Month 1Sandbox conversionCMS converted from a copy of EP1; custom code and downtime measured
- Month 3Development convertedCMD built from a copy of ED1; dual maintenance starts
- Month 4Quality convertedCMQ built from a copy of EQ1; integration testing begins
- Months 5 to 8Mock conversions and rehearsalTwo mock conversions on production copies, then the dress rehearsal in CMQ refreshed from production
- Go-live weekendProduction convertedEP1 becomes CMP; the ECC maintenance line is retired
Running retrofit
- Fix in maintenanceAn urgent fix goes through ED1 → EQ1 → EP1 under ChaRM
- Log for retrofitThe change is added to the retrofit list with its transport and owner
- AssessDoes the object still exist in S/4HANA, or was it replaced?
- Rebuild in projectThe same change is made in CMD, adapted where needed
- Test and closeRetested in CMQ; the retrofit list entry is closed with evidence
SAP Solution Manager offers tool support for retrofit in dual landscapes, including cross-system object locks, and SAP's knowledge base points to its configuration. Contoso's ECC line had that support; the S/4HANA project line in SAP Cloud ALM handled retrofit by procedure, with a list reviewed weekly. Check SAP's current roadmap before assuming a tool covers your retrofit. To keep the list short, Contoso froze ECC changes except legal and urgent fixes from the first mock conversion onward.
After go-live: do you still need two lines?
After go-live the question returns. Contoso's next project is Wave 2: loading Alternadores del Norte into company code 1910, with new configuration for Mexico, while production support continues. The team compared two designs.
| Design | How it works | Strengths | Costs |
|---|---|---|---|
| Single track with release timeboxes | One line CMD → CMQ → CMP; project features held back until their release date; urgent fixes deployed between releases | No retrofit; fewer systems | Work in progress must be switched off or kept out of transports; needs discipline |
| Five-system dual track | Project line (development and test) beside maintenance line (correction, quality, production) | Fixes never wait for project work | Retrofit for every fix; two more systems to pay for and refresh |
SAP's documentation for the ABAP environment on SAP BTP describes both patterns in detail. One codeline in a three-system landscape suits occasional development where the team can pause for an urgent fix. One development and one correction codeline in a five-system landscape suits permanent development with many developers: after a cut-off date, defects are fixed in the correction system and maintained in parallel in development. The same reasoning applies to an S/4HANA landscape.
- Will project work and urgent fixes overlap on the same objects for months?Yes → consider a dual track · No → single track with timeboxes
- Can unfinished features be kept out of production transports reliably?Yes → single track is workable · No → dual track or stronger release discipline
- Can the team staff retrofit and the extra test cycles?Yes → dual track is viable · No → reduce parallel change instead
What would you do?
Two weeks before Contoso's go-live, Ana reports a payment block bug in ECC production. Sam fixes it in ED1 and imports it to EP1. What else must happen?
- A dual track separates maintenance from project work; its price is retrofit.
- SAP's conversion sequence: sandbox, development, quality, rehearsal, production, with a short gap between development and production.
- Freeze the maintenance line as far as possible to keep retrofit small.
- After go-live, choose between single track with timeboxes and a five-system dual track by overlap, discipline and capacity.
Check your understanding · not graded
Lesson check
1. What is retrofit?
2. Why does SAP advise a short gap between converting development and production?
3. In the five-system pattern, where are defects fixed after the cut-off date?
4. What keeps a retrofit list short during a conversion?