Access historical ERP data from SAP S/4HANA

In principle, there are only two ways to transition from any ERP system to SAP S/4HANA. One could either install SAP S/4HANA from scratch, which is often called Greenfield, or convert their current ERP system to SAP S/4HANA, if it fulfilled the requirements as per SAP Note 2290622 – SAP Readiness Check for SAP S/4HANA, often called Brownfield. Pretty much four years ago I wrote a blog How to decide between a Greenfield and Brownfield S/4HANA transition. Any other options can only be variants of those two and are quite often driven by the question how to access historical ERP data from SAP S/4HANA, which is the topic of this blog.

Why is historical ERP data different from current ERP data when it comes to SAP S/4HANA?

Greenfield

1. As with any other SAP ABAP based system, data should always be loaded through the business logic into SAP S/4HANA. For historical data, this is however not always possible because for example of historic posting periods already closed or other required master data missing.
2. With sophisticated tools that for example SAP SLO use, it is possible to circumvent the business logic and directly load into SAP S/4HANA tables. While this is a valid approach in circumstances like for example the Euro conversion at the time, I would not recommend this to access historic ERP data from SAP S/4HANA for three reasons:
   1. Since there is no check from the business logic, data that is not completely business ready might be loaded. As one of the advantages of SAP S/4HANA is to directly report from operational data, former ETL steps to cleanse data into BW systems to overcome this issue should in my opinion be omitted.
   2. More importantly though, loading directly into SAP S/4HANA tables is in most cases unnecessary, because modern solutions like SAP S/4HANA do not need all data local to them any longer, since they provide and consume their data via APIs, namely the SAP Fiori Technology.
   3. And not to forget, data in memory storage is still more expensive than in other storage technologies. Once loaded in memory, storing colder data in other storage could be achieved with for example with Data Aging, but why make it complicated in the first place?

Brownfield

1. Technically, if possible, an ERP conversion to SAP S/4HANA is an upgrade leveraging the SAP Software Update Manager. However, since SAP S/4HANA is a new product, this is different from a license perspective and needs to be taken care of. Also, since in SAP S/4HANA many data structures have been simplified, the upgrade procedure has a lot more to do and, in some cases, simply fails because of inconsistent historical data for example due to former M&A activities.
2. Again, with sophisticated tools that for example SAP SLO use, it is possible to circumvent the upgrade logic and directly load into SAP S/4HANA tables. While this is a valid approach in circumstances like extreme downtime optimization where SAP Note 2163060 – Prerequisites and restrictions of Zero Downtime Option of SUM for SAP Business Suite does not apply, I would usually not recommend this to access historical ERP data from SAP S/4HANA for three reasons mostly identical to the above:
   1. Since there is no check from the upgrade logic, data that is not completely business ready might be loaded. As one of the advantages of SAP S/4HANA is to directly report from operational data, former ETL steps to cleanse data into BW systems to overcome this issue should in my opinion be omitted.
   2. More importantly though, loading directly into SAP S/4HANA tables is in most cases unnecessary, because modern solutions like SAP S/4HANA do not need all data local to them any longer, since they provide and consume their data via APIs, namely the SAP Fiori Technology.
   3. And not to forget, data in memory storage is still more expensive than in other storage technologies. Once loaded in memory, storing colder data in other storage could be achieved with for example with Data Aging, but why make it complicated in the first place?

What are potential alternatives?

Greenfield

1. Install fresh SAP S/4HANA system.
2. Configure fresh SAP S/4HANA system.
3. Migrate master data either with the SAP Migration Cockpit or SAP Advanced Data Migration by Syniti depending on the complexity of your data and your business requirements.
4. Migrate current data either with the SAP Migration Cockpit or SAP Advanced Data Migration by Syniti depending on the complexity of your data and your business requirements.
5. Migrate historical data into appropriate storage with either any ETL tool or again SAP Advanced Data Migration by Syniti depending on the complexity of your data and your business requirements.
6. Build SAP HANA Core Data Services (CDS) views to combine actual with historical data.
7. Extend SAP Fiori apps to use the CDS views instead of the original tables.

Brownfield

In case the ERP system is convertible:

1. Archive cold data.
2. Convert ERP system.

In case the ERP system is not convertible:

1. Create shell copy.
2. Including customizing.
3. Migrate master data either with the SAP Migration Cockpit or SAP Advanced Data Migration by Syniti depending on the complexity of your data and your business requirements.
4. Perform process transformations and simplifications.
5. Convert to SAP S/4HANA.
6. Migrate current data either with the SAP Migration Cockpit or SAP Advanced Data Migration by Syniti depending on the complexity of your data and your business requirements.
7. Migrate historical data into appropriate storage with either any ETL tool or again SAP Advanced Data Migration by Syniti depending on the complexity of your data and your business requirements, build SAP HANA Core Data Services (CDS) views to combine actual with historical data and extend SAP Fiori apps to use the CDS views instead of the original tables.

• Source: https://blogs.sap.com/2020/04/15/access-historical-erp-data-from-sap-s-4hana/