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Former Member

Data Transfer Through Files

Introduction:

One of the new feature of SAP TDMS 4.0 is data transfer through files.It is considered to be one of major enhancement in TDMS 4.0.

File transfer method is different from standard TDMS packages as it does not require the RFC destinations to all the involved system.

File-Based Transfer separate Data Selection and Data Transfer process by introducing


1. An Export Package - Standard TDMS Package without receiver related actions

2. An Import Package –  Allows a data transfer to selected receiver system

The figure below shows the main steps to be followed in both contexts (export and import package)

The export package requires Sender system,control system,Central system and a file system where data will be extracted.

The import package requires a dummy sender system, where SAP TDMS can create the cluster DMC_INDXCL and import files to the cluster.

The dummy sender system can be the receiver system, the control system, or a different system not used during export.

Why File-Based Transfer :

File -based transfer can be used in following contexts(which cannot be achieved through RFC based transfer):

1.There is no direct connection between the sender system and the receiver system.

Scenarios:

  • Sender (Production/production snapshot) is ready to send data but the test system is not yet ready to receive it since it is down for maintenance or is being installed using TDMS shell creation method. Everything is on hold until test system is online. I wondered at such times if there was a way I can export data (similar to SAP Sapinst export/import method used in system copy) and store it in the file system which I can then import when receiver system is available.
  • Due to security reasons, the sender system is not allowed to connect to non production systems via RFC. It is not therefore possible to use RFC means to extract data.

Both of these problems can be addressed via this new TDMS functionality.

2. If one want to carry out multiple imports of test data using a single export file.- With the single export file,one can carry out multiple imports into various non production systems.This reduces the effort and time of running data export every time. Remember that data import take relatively less time than data extraction.

3. Sender and receiver systems are in different data centers located in different geographical areas.In such cases, RFC based transfer takes lot to time due to slow network bandwidth between data center.One can overcome this limitation by running export package involving systems residing in same data center,move the data extract file to other data center and run import package there.


Things to do before using file-transfer method:

1. Definition of Data Extract Export and Import Directory :

Specify the export and import directory for the data extract files by defining the logical path DMIS_DEX_ROOT in the SAP transaction-'File'.

By default, the logical path DMIS_DEX_ROOT points to the transport directory DIR_TRANS that is defined in the system profile of the respective Data Transfer Control system


While choosing the export and import directory,keep in mind that it should have space available for data files which are going to be placed at that location.

The space required depends on the sender database size and type of reduction scenarios used.One such example, data files amounting 100 GB of space is extracted from 4 TB database using 1 year data reduction scenario(Time base reduction).

Export or import path can be assigned using any one of the following methods:

-Change the definition of the logical path DMIS_DEX_ROOT in the control system by using transaction FILE.

-Create own logical path definitions and assign them as the new logical export or import path by using transaction CNV_MBT_DEXDEFAULTS in the control system.

2.Definition of Maximum File Size for Data Extract Data Files:


One can change the maximum size for each data extract file by defining a corresponding maximum file size in bytes using transaction CNV_MBT_DEXDEFAULTS for the control system.Please don't keep maximum size more than 500 MB as it can cause runtime errors(TSV_TNEW_PAGE_ALLOC_FAILED,SYSTEM_NO_ROLL) during data extraction phase.

Steps involved in File transfer method :

1. Creating export package:

  • Create appropriate TDMS migration package for the required application.

  • Specify –‘file based transfer ‘as Method of Transfer in the first execution step of the package.

By default, SAP TDMS chooses RFC-based data transfer. Change the mode of transfer to data transfer through files by choosing Mode 2.

  • Define a data extract id for file transfer: In data transfer phase, execute the activity -Defining a Data Extract ID for File Transfer.

Other steps in process tree are quite similar to the RFC based transfer method.

Once export package is complete,transfer the files to receiver system

2. Creating an Import Package :

  • Create a new import package to import data through files by choosing appropriate solutions from TDMS portfolio.


The migration process tree for data import contains the following new activities:

- Identification of Data for File Import :

Assign a data extract to the import package by executing the Select Data Extract for Import activity. Enter the data extract ID,press Enter then click Assign button.

- Start of File Import:

Execute the Start Data Extract Import activity to import the data to the data cluster DMC_INDXCL in the defined sender system.

Other steps in process tree are quite similar to the RFC based transfer method.

This (file based transfer) is what I consider to be major enhanced feature of SAP TDMS 4.0. There are several other improvements which I have not included in this blog.


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