Lesson 3 of 5
Mix and match
10 min
Mix and match starts from the other end. You install a new, clean SAP S/4HANA system and then bring across only the elements of existing configuration and ABAP repository that you want to keep, by transport or by manual transfer. Business data then follows selectively, as in a shell conversion. SAP Learning positions it for programs where the majority of the solution is being redesigned but some proven parts are worth keeping.
- Install a new systemStart from SAP S/4HANA standard, optionally with SAP Best Practices content
- Decide per elementReuse, redesign or retire each configuration area and custom object
- Transfer what is reusedMove selected customizing and code by transport or rebuild by hand
- Build the new designRedesigned processes configured fresh
- Transfer data selectivelyMaster data, open items and any history, in repeated cycles
- CutoverFinal selective transfer into production
Reuse, redesign or retire
The heart of mix and match is a long list of decisions, one per configuration area and custom object. Each one is reuse (bring it over, adapted if needed), redesign (build it new in SAP S/4HANA), or retire (leave it behind). Usage data helps: if a custom report has not been run in two years, the burden of proof is on whoever wants to keep it.
| Element | Decision | Reason | Contoso what-if example |
|---|---|---|---|
| Pricing procedure for fleet customers | Reuse | Proven, contractually agreed, little to gain from redesign | Fleet pricing for Great Lakes Fleet Services |
| Credit management | Redesign | SAP S/4HANA uses a different credit management design | New credit limits and checks for fleet customers |
| Custom warranty claim screen | Retire | Replaced by a standard app; unused for months | No longer needed |
| Custom alternator test-certificate printout | Reuse with adaptation | Customers require it; code must be adapted | Certificate printed for CMC-ALT-100 deliveries |
Element-level decisions in a mix and match, shown as a Contoso what-if. Every "reuse" still needs adaptation checks and testing.
- Is the element still used and does it still fit the target design?Yes → candidate for reuse · No → retire
- Does SAP S/4HANA standard now cover it?Yes → redesign on standard (clean core) · No → reuse and adapt
- Is it compatible with the SAP S/4HANA data model?Yes → transfer by transport · No → adapt or rebuild before transfer
Shell conversion or mix and match?
Both variants end with a selective data transfer. What differs is where the target system comes from and therefore how much of the old system you inherit by default. In a shell conversion, you inherit everything and must remove what you do not want. In mix and match, you inherit nothing and must add what you do want. The default matters, because things nobody decides about end up on the default side.
| Question | Shell conversion | Mix and match |
|---|---|---|
| Starting point | Copy of production without business data, converted | New installation |
| Default for old configuration and code | Carried unless removed | Left behind unless selected |
| Best fit | Most processes reused | Most of the solution redesigned |
| Effort and cost | Usually lower | Usually higher, because more is designed and selected one by one |
| Double maintenance | From shell copy to cutover | Smaller, limited to the elements being reused |
| Main testing focus | Regression of converted processes plus data transfer | Full functional testing of the new design plus data transfer |
Data still has to come across
Neither variant moves business data by itself. In both, the data transfer is a separate stream with its own design, transfer programs, test cycles and reconciliation. That stream is where most SDT risk lives, and it is the subject of the next two lessons.
What would you do?
In a mix and match, a developer proposes transporting all 1,400 custom objects from ECC into the new system "so nothing breaks", and deciding later which to keep. What should the program do?
- Mix and match installs a new system and brings across only selected configuration and code.
- Each element is reused, redesigned or retired; usage data and process owners drive the decision.
- Shell conversion inherits by default; mix and match leaves behind by default.
- Both variants still need a separate, rehearsed selective data transfer.
Check your understanding · not graded
Lesson check
1. Mix and match starts with which target system?
2. Which variant is usually more effort and cost?
3. What happens to an old configuration element nobody decides about in mix and match?
4. A custom report has not been run in two years. What is the likely decision?