If your project involves moving from a legacy system to SAP then you need to migrate data from legacy system to SAP system. On most projects this is the case. Let us see how it is done and what kind of issues are faced in real world scenario.
First of all why data migration is needed? It is because the end users who were using the legacy system will move on to SAP system and they must have old data from legacy system on the SAP system so that they can continue their work on the new system without having to manually re-enter a large amount of data in the new SAP system.
Activities involved in data migration include purging, cleansing legacy data, data mapping, and finally migration of cleaned and mapped data into the SAP system. The first task in data migration is to purge legacy data. Data which will not be used in SAP system must be purged. the next step is to map legacy data to SAP format. Data from which legacy system table will be fetched for which table in SAP system need to be identified. What is the format of the fields in the legacy system table and how the format need to be changed as per the table in SAP system to be decided. Once you get the cleaned and mapped data then you feed this data into the SAP system.
There are some good tools used for data migration. In SAP, LSMW (Legacy System data Migration Workbench), eCATT etc. tools are in built for doing data migration. eCATT is actually a testing tool but is used often in data migration as well. There are also third party data migration tools available. In real life some amount of data is migrated manually and rest is migrated using automated tools.
In the new SAP system master data need to be populated and only then it can be used by end users. this master data can be entered manually but if a tool is available which can copy the master data from legacy system, format it and then push the data in the SAP system then it will be faster to do so.
There will also be transaction data in the legacy system which need to be migrated. The transaction data is of 2 types. One is current transaction data and another is archive data. Archive data consists of closed POs, PRs etc. The current transaction data consists of open POs, PRs, other purchase documents, inventory balance etc.
archive data need to be migrated to SAP system because they are used for legal compliance reports, financial reports etc. Migrating archive data does not pose much problem. the only issue here is that you need to contain amount of archive data. Unnecessary archive data migration may only add to your labor cost with no benefit to your client. If your client needs to keep data from previous 7 years as statutory compliance then there is no need to migrate data which is beyond those 7 years.
You need to be very careful about migrating current transaction data. there will be open PO, PRs etc. I will talk about these issues in my next post.