Module 2: BW/4HANA System Architecture
This module provides a deep architectural understanding of BW/4HANA, focusing on:
- LSA vs LSA++ architecture
- Data warehousing layers in detail
- BW/4HANA system landscape
- Modeling tools (Eclipse-based)
- BW/4HANA vs ECC-based BW
Architecture knowledge is mandatory for:
- Correct modeling
- Performance optimization
- Interview discussions
- Designing scalable BW solutions
1. What is BW/4HANA System Architecture?
BW/4HANA system architecture defines:
- How data flows end-to-end
- How responsibilities are separated
- How scalability and performance are achieved
- How modeling aligns with HANA pushdown
BW/4HANA architecture is conceptual and layered, not object-heavy.
2. Layered Scalable Architecture (LSA)
2.1 What is LSA (Classic)?
LSA (Layered Scalable Architecture) was SAP’s recommended architecture for classic BW.
Core Characteristics of LSA
- Strong persistence at every layer
- Multiple physical layers
- Heavy use of DSOs, InfoCubes, MultiProviders
- Aggregates for performance
Typical Classic LSA Flow
Source
↓
PSA
↓
DSO (Staging)
↓
DSO (Harmonization)
↓
InfoCube
↓
MultiProvider
↓
BEx Query
High data redundancy
Long load times
Complex maintenance
Heavy dependence on aggregates
Poor flexibility
3. Layered Scalable Architecture Plus Plus (LSA++)
3.1 What is LSA++?
LSA++ is SAP’s modern reference architecture, optimized for HANA and BW/4HANA.
It replaces:
- Data redundancy → Virtualization
- ETL → ELT (pushdown)
- Aggregates → On-the-fly calculation
Core Principles of LSA++
Logical layers, not mandatory physical layers
Push logic to HANA
Persist only when necessary
Reuse models
Virtualize wherever possible
LSA vs LSA++ (Key Comparison)
| Aspect | LSA (Classic BW) | LSA++ (BW/4HANA) |
|---|---|---|
| Database | Any | SAP HANA only |
| Persistence | Heavy | Minimal |
| Aggregates | Required | Not needed |
| Objects | Many | Simplified |
| Pushdown | Limited | Core principle |
| Flexibility | Low | High |
LSA++ focuses on logic pushdown and virtualization instead of persistence.
4. Data Warehousing Layers in LSA++
LSA++ defines logical layers. Not all layers must be physical.
4.1 Data Acquisition Layer
Purpose
- Bring data from source systems
- Minimal transformation
Objects Used
- ODP-based DataSources
- Open ODS Views
- PSA (optional)
Best Practices
- Keep transformations technical only
- Do not apply business rules
- Keep data source-aligned
4.2 Corporate Memory / Staging Layer
Purpose
- Store raw, historical data
- Enable reprocessing and auditing
Objects Used
- aDSO (Standard type)
Best Practices
- Persist only if audit/history is required
- Avoid unnecessary data duplication
4.3 Harmonization Layer
Purpose
- Apply business logic
- Integrate multiple sources
- Harmonize keys and master data
Objects Used
- aDSO (Standard)
- AMDP-based transformations
Best Practices
- Centralize business logic
- Avoid repeating logic in queries
- Use HANA pushdown where possible
4.4 Reporting / Virtualization Layer
Purpose
- Combine data virtually
- Enable reuse
- Avoid data persistence
Objects Used
- CompositeProviders
- Open ODS Views (virtual)
Best Practices
- Avoid one-off CompositeProviders
- Design reusable models
- Do not persist reporting-only data
4.5 Consumption Layer
Purpose
- Enable analytics and reporting
Objects Used
- BW Queries
Consumers
- SAP Analytics Cloud
- Analysis for Office
- Third-party BI tools
Best Practices
- Keep logic presentation-focused
- Avoid data cleansing here
5. BW/4HANA System Landscape
Typical BW/4HANA Landscape
DEV → QA → PRD
Landscape Characteristics
- Separate BW/4HANA system (recommended)
- Integrated with S/4HANA, ECC, non-SAP
- Uses CTS for transports
BW/4HANA should be a central analytics system, not mixed with OLTP.
6. Modeling Tools Overview
BW Modeling Tools (Eclipse)
BW/4HANA modeling is done using BW Modeling Tools (BWMT) in Eclipse.
What Can Be Modeled in Eclipse?
- InfoObjects
- aDSOs
- CompositeProviders
- Transformations
- DTPs
- BW Queries
- Process Chains
Why Eclipse-Based Modeling?
Better performance
Better UI
Version control friendly
Required for modern BW features
SAP GUI modeling is not recommended for BW/4HANA.
7. BW/4HANA vs ECC-Based BW
Architectural Comparison
| Area | ECC-Based BW | BW/4HANA |
|---|---|---|
| Database | Any | SAP HANA |
| Modeling | SAP GUI | Eclipse |
| Objects | Legacy-heavy | Simplified |
| Performance | Aggregate-based | Pushdown-based |
| Future | Maintenance | Strategic |
Strategic Direction
BW/4HANA is the only strategic BW platform going forward.
8. Common Architecture Mistakes
Over-persisting data
Ignoring LSA++ principles
Mixing classic and modern patterns
Applying logic in wrong layers
9. Interview-Grade Explanation
Q: Explain LSA vs LSA++ in BW/4HANA.
Answer:
LSA is the classic layered architecture used in traditional BW systems with heavy persistence and aggregates. LSA++ is the modern architecture for BW/4HANA that leverages HANA pushdown, virtualization, reduced persistence, and simplified modeling to achieve better performance and scalability.
10. Summary
- BW/4HANA uses LSA++ architecture
- LSA++ reduces persistence and complexity
- Layers have clear responsibilities
- Eclipse-based modeling is mandatory
- BW/4HANA is architecturally different from ECC BW
11. What’s Next?
➡️ Module 3: BW/4HANA Data Modeling Basics (InfoObjects)
Architecture decisions made early determine performance, scalability, and maintenance cost.