Dear,
Please have a look at below :
Start data migration from the legacy business systems to the ERP system as soon as possible.
A real configuration of an ERP system will only happen when there is real data in the system. The mapping of legacy system data to a new ERP is a long difficult process, and choices must be made as to what data gets moved and what gets left behind. The only way to verify what you need to actually run in the new ERP environment is to migrate the data over to the ERP development and test environments and test it. The only way to get a smooth transition to a new ERP is to develop processes as automatic as possible to migrate the data from the old system to the new.
Data loading is not a project that can be done after everything else is ready. Just defining the data in the legacy system is a huge horrible task. Actually mapping it to one of the ERP system schemas is a lesson in pain that must be experienced to be believed.
The scope of a data migration project is usually a fairly large development process with a lot of proprietary code written to extract legacy data, transform and load the data into the ERP system. This process is usually called ETL (extract, transform, load.)
How is data put into the ERP?
There is usually a painfully slow data import facility with most ERP systems. Mashing data into the usually undocumented table schema is also an option, but must be carefully researched. Getting the data out of the legacy systems is usually left to the company buying the ERP. These export - import processes can be complex and slow, sometimes specialized ETL tools can help, sometimes it is easier to use what ever your programmers are familiar with, tools such as C, shell or perl.
An interesting thing to note is that many bugs and quirks of the old systems will be found when the data is mapped and examined. I am always amazed at what data I find in a legacy system, usually the data has no relational integrity , note that it does not have much more integrity once it is placed in an ERP system so accurate and clean data going in helps to create a system that can work.
The Business Analysts (BAs) that are good understand the importance of data migration and have an organized plan to migrate the data, allocate resources, give detailed data maps to the migrators (or help create the maps) and give space estimates to the DBAs. Bad BAs can totally fubar the ERP implementation. If the BAs and management cannot fathom that old data must be mapped to the new system, RUN AWAY. The project will fail.
SAP Data Migration with LSMW
No ABAP effort are required for the SAP data migration. However, effort are required to map the data into the structure according to the pre-determined format as specified by the pre-written ABAP upload program of the LSMW.
The Legacy System Migration Workbench (LSMW) is a tool recommended by SAP that you can use to transfer data once only or periodically from legacy systems into an R/3 System.
More and more medium-sized firms are implementing SAP solutions, and many of them have their legacy data in desktop programs. In this case, the data is exported in a format that can be read by PC spreadsheet systems. As a result, the data transfer is mere child's play: Simply enter the field names in the first line of the table, and the LSM Workbench's import routine automatically generates the input file for your conversion program.
The LSM Workbench lets you check the data for migration against the current settings of your customizing. The check is performed after the data migration, but before the update in your database.
So although it was designed for uploading of legacy data it is not restricted to this use.
We use it for mass changes, i.e. uploading new/replacement data and it is great, but there are limits on its functionality, depending on the complexity of the transaction you are trying to replicate.
The SAP transaction code is 'LSMW' for SAP version 4.6x.
For those with the older SAP version (4.7 and below), the data migration programs might not have been pre-loaded.
You can download the LSMW at no cost from SAPNet under Services, SAP Methodology and Tools, category Tools.
If you are an existing SAP customer with an OSS ID, you can access the SAP Service Marketplace to download the LSWM for your Basis teams to install to your SAP system: http://service.sap.com/lsmw
The LSM Workbench carries out the following tasks:
Reads the transfer data from one or more files (for example, spreadsheets, sequential files etc.)
Converts the data from the source format into the target format
Note that with background processing, the input file must not be located in the presentation server. Access to presentation server files is only possible when you are working online.
http://www.s-ox.com/dsp_getNewsDetails.cfm?CID=1865
Regards,
Syed Hussain.
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