Conversion to S/4 vs. selective migration of historical data

We outline how to safely migrate data to S/4, what scenario to choose and what tools to use to reduce the amount of data.

Let’s look at different migration scenarios with a focus on data migration.

Greenfield. In this approach – implementing the system from scratch – we start using new S/4 functions and technologies without access to historical data. The focus is on adapting the system to business processes. An additional data migration project (open items, opening balances) is required to be able to use backward analyses.

Brownfield. This is the opposite approach. We do not change business processes. I transfer all the history and all the data to the new system. Migration is in fact a technical upgrade of the system to a new version and a faster database.

Bluefield. This approach combines the best of both of the above ones. We move to a new version of the system, and at the same time we flexibly improve processes and can selectively migrate historical data. We can perform the migration quickly – during the weekend (we start on Friday evening, finish it on Saturday evening and hand over the finished system to the customer so that they can test it on Sunday and provide it to users on Monday). This time can be further shortened in the “near zero downtime" approach. The time needed for migration depends on the size of the system and the complexity of the project. It is worth noting that we are not dependent on the fiscal year, we can perform the migration at any time.

Slimming down the system – why and how

The reasons for selecting historical data may vary. They can be divided into two main categories.

In some circumstances it is necessary. For example, in the case of the sale of a business unit, when a system is carved out for another entity, however without master data (it is especially necessary to protect sensitive data, such as financial data, addresses, account numbers, etc.). Another reason is the size of the system. A large amount of data makes it necessary  to plan the system downtime for the time of migration. Not every company can afford this, and then there are demands to get rid of unnecessary ballast and reduce the amount of transferred data.

The second category of reasons is the desire for optimization. Reducing the amount of data improves the efficiency of the system’s operation, thus speeding it up. Historical data is often unnecessary ballast that can be disposed of without harming the business. And finally – a smaller data volume makes it easier to implement other transformation scenarios in the same project as migration to S/4 (e.g., harmonization and consolidation of a chart of accounts or business partner).

In Bluefield, an in-house developed approach, we use the CrystalBridge platform offering a wide portfolio of tools that automate migration activities, including data migration.

Data migration in a typical S/4 migration project

The distinguishing feature of the Bluefield approach in migrating to S/4 is the creation of an empty copy of the system (without data), and then its conversion to S/4. This creates a golden copy of the system, ready to receive data. The next step is a test migration. It is followed by verification, user testing, patching and specification refinement. We perform several iterations of migration, testing and patching. This is a continuous process to catch all errors. Usually it has from 2 to 5 cycles, depending on the complexity of the project. The last cycle – a final rehearsal (to improve efficiency and draw up a detailed schedule) is followed by go-live.

In the analysis phase – even before accessing the customer’s system, we use System Scan, a tool that presents in an attractive visual form what the system contains, how individual data and processes are used.

CrystalBridge Transformation Cockpit allows us to select data based on the organizational structure or based on time.

The selection based on the organizational structure (for example, in FI – a company code, SD – a sales department, MM – a plant, CO – a controlling area) occurs in almost every type of an SAP transformation project. The second option – selection based on time (usually a fiscal year or a selected date) is possible for each SAP area, in a detailed (tabular) approach or in an aggregated (BAPI) approach.

What about the historical data?

And what happens to the old data? Several approaches are possible. Depending on the type of data and the customer’s decision, historical data can be archived 1:1 (we cooperate with a subcontractor that specializes in archiving transformations), we can store it in a data warehouse (in BW we can transform data with tools available in BW standard or use solutions provided by our company). Old data can also be simply deleted.

Automated tests

Automated tests are one of the tools that, after selective data migration, allows us to check whether we have actually packed into the target system the data that is needed for the proper operation of business processes. They can also help us check the configuration. The key advantages of automated tests are:

• They are independent of the user interface;
• They contain predefined test scenarios;
• They allow for flexible selection of the scope of the tested data;
• They enable the test log to be tracked;
• The preparation of customer-specific test objects does not require much effort;
• They do not require additional equipment.

Another tool is Data Consistency Verification. It is used to check connections between individual tables and fields and to verify data integrity. The solution provides:

• Technical verification of data integrity of the entire system;
• Fully automatic control;
• Only the evaluation of identified inconsistencies and their inclusion in the implementation must be done manually by the user;
• Three types of verification: foreign keys, domain values and fixed domain values.

And finally, good advice. After moving to a new place, it’s a good idea to keep master data organized. SAP offers a dedicated tool to maintain data integrity – Master Data Governance. All for One also offers its customers support in this area.