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17.8 Shell Conversion & Migration

1. What shell conversion does​

SAP BW bridge provides shell-conversion capabilities for supported BW and BW/4HANA releases.

Current SAP documentation states that shell conversion can transfer metadata objects such as:

  • DataStore objects,
  • InfoObjects,
  • transformations,
  • DTPs.

Existing data records are not transferred by shell conversion.

2. Migration mental model​

Legacy BW/4HANA
       |
metadata conversion
       |
BW bridge shell
       |
reload / reconnect source data
       |
validate
       |
modernize

3. Why data is not the same as metadata​

A metadata migration establishes the model.

Data migration still requires:

  • source connectivity,
  • initial loads,
  • delta processing,
  • historical validation,
  • reconciliation.

Never treat a successful shell conversion as a completed migration.

4. Migration waves​

A safe enterprise migration can use:

Wave 0 — Discovery​

Inventory objects, consumers, dependencies and criticality.

Wave 1 — Low-risk workloads​

Move non-critical models.

Wave 2 — Shared enterprise models​

Migrate high-reuse models with stronger validation.

Wave 3 — Critical finance and regulatory workloads​

Use parallel run and explicit cutover criteria.

Wave 4 — Optimization​

Remove redundant historical layers and retire legacy objects.

5. Migration scoring​

Score each workload on:

  • business criticality,
  • complexity,
  • consumer count,
  • source complexity,
  • transformation complexity,
  • unsupported features,
  • performance risk,
  • regulatory sensitivity.

6. Cutover rule​

Do not cut over because:

"The new model works."

Cut over when:

  • data reconciles,
  • consumers validate,
  • performance meets SLO,
  • security is approved,
  • recovery is proven,
  • rollback is understood.

Exercise​

Build a migration wave plan for 1,000 BW objects with 8,000 consumers.

Define objective entry and exit criteria for every wave.