SAP REPLICATION SERVER

v SAP Replication Server (SRS) also known SAP Sybase Replication Server is a real-time data integration and movement software.

v SAP Replication Server (SRS) moves and synchronizes transactional data including DML and DDL across the enterprise, providing low impact, guaranteed data delivery, real-time business intelligence, and zero operational downtime.

Note: SAP ASE - SAP Adaptive Server Enterprise (SAP ASE)

Introduction to Replication Agents

A Replication Agent is an SAP Replication Server client that retrieves information from the transaction log for a primary database and formats it for the primary Replication Server. RepAgent is the Replication Agent component for SAP ASE.

Replication Agent detects changes to primary data and ignores changes to nonprimary data. Using Log Transfer Language (LTL), a subset of Replication Control Language (RCL), Replication Agent sends changes in primary data to the primary SAP Replication Server, which distributes the information to replicate databases.

The Replication Agent connections status is derived from the status of the Replication Agent thread in the SAP Replication Server, and the status of the Replication Agent process that is extracting data from the primary database. You can use SAP® Control Center for Replication to monitor the Replication Agent thread or the Replication Agent process and alert you if any Replication Agent has stopped running.

SAP provides Replication Agent components for other non-SAP ASE data servers, including IBM DB2 Universal Database, Microsoft SQL Server, and Oracle. See the Heterogeneous Replication Guide and the Replication Server Options documentation for the databases actively supported by SAP Replication Server.

Replication Agent for DB2 is the Replication Agent component for the z/OS-based DB2 Universal Database. SAP Replication Agent is the Replication Agent component for DB2 Universal Database (on UNIX and Windows platforms), Microsoft SQL Server, and Oracle.

RepAgent is an SAP ASE thread. Replication Agent for DB2 is a separate process that resides on the z/OS host. SAP Replication Agent is a separate application that resides on a UNIX or Windows host.

Basic Replication System

A basic SAP replication system consists of a primary SAP ASE database, a SAP Replication Server, and a replicate SAP ASE database.

SAP ASE includes all the features necessary to support an SAP replication system, with no additional components other than the SAP Replication Server.

The three components include:

v Primary database – a database in which original data-changing operations (or transactions) are performed. Only completed transactions are captured for replication.

v SAP Replication Server – an Open Client and SAP Open Server product that receives transactions to be replicated from a primary database, and delivers them to a replicate database.

v Replicate database – a database that receives replicated transactions from a Replication Server and applies those transactions to its own “copy” of the primary data.

You can use system management tools such as SAP Control Center, to manage your replication system.

The basic SAP replication system diagram illustrates the flow of data between two Adaptive Servers and a Replication Server.

Data flows from the primary database to the Replication Server, and then to the replicate database.

Heterogeneous Replication System

A heterogeneous SAP replication system consists of data-changing operations between two databases of the same or different vendors (except ASE to ASE).

For information on ASE to ASE replication, see the Replication Server Administration Guide Volume 1 and Volume 2.

  Heterogeneous replication includes:

A replication system in which Adaptive Server Enterprise (ASE) is either the primary or the replicate data server, and a non-ASE data server (such as IBM DB2 UDB) is the other data server.

A replication system in which the primary and replicate data servers are both non-ASE data servers (for example, Oracle is the primary data server and IBM DB2 UDB is the replicate data server, or Microsoft SQL Server is the primary server and Microsoft SQL Server is the replicate server).

ASE was enhanced to support Replication Server. All of the data server elements required to support Replication Server (that is, a data-change capture mechanism in the primary database, and system tables and stored procedures in the replicate database) are either built into Adaptive Server Enterprise or enabled by utilities that are provided with the Replication Server or Adaptive Server software.

Additional components are required to implement an SAP replication system with non-ASE data servers:

·        A Replication Agent

·  Enterprise Connect Data Access for ODBC (for Microsoft or DB2 UDB) or ExpressConnect (for Oracle or for SAP HANA database), which are required if the replication data server connectivity requirements are not compatible with Replication Server

·  The diagram illustrates a typical SAP replication system with non-ASE data servers, showing the flow of data between the data servers, through:

·  Replication Agent, Replication Server, and Enterprise Connect Data Access (ECDA) database gateway, and,

·      Replication Agent, Replication Server, and ExpressConnect (for Oracle or for SAP HANA database).

If you are using ECDA database gateways, data flows from the primary database to the Replication Agent, from the Replication Agent to the Replication Server, from the Replication Server to the ECDA database gateway, and then from the database gateway to the replicate database.

ECDA database gateways support IBM DB2 UDB and Microsoft SQL Server by providing connectivity between Open Client and SAP Open Server and ODBC to the replicate data server, and by providing SQL transformation and other services. Replication Server also includes datatype support for non-ASE data servers.

If you are using ExpressConnect (for Oracle or for SAP HANA database, data flows from the primary database to the Replication Agent, from the Replication Agent to the Replication Server, and then from the Replication Server directly to the replicate database.

Replication Agents support non-ASE primary data servers by reading the completed transactions in the primary database and sending them to Replication Server for distribution.

SAP Replication System Components

The replication system components are described by their function and role in an SAP replication system.

The replication system components include:

v Primary data server

v Replication Agent

v Replication Server

v A connector to the replicate database, such as:

o   Enterprise Connect Data Access

o   ExpressConnect for Oracle

o   ExpressConnect for SAP HANA Database

v Replicate data server

Primary Data Server

A primary data server manages one or more primary databases, which are the sources of the data-changing operations or transactions in a replication system. The primary data server is configured to capture information needed for replication.

All primary data servers are supported by Replication Agents. ASE has an internal Replication Agent. The non-ASE servers require an external Replication Agent

Supported Primary Database Servers

SAP replication technology actively supports transaction replication from different relational database servers aside from Adaptive Server Enterprise.

1. IBM DB2 UDB on z/OS

2. IBM DB2 UDB on UNIX/Windows

3. Microsoft SQL Server

4. Oracle

Replication Agent

Replication Agent transfers transaction information, which represents changes made to data schemas and execution of stored procedures, from a primary data server to a Replication Server, for distribution to other (replicate) databases.

A Replication Agent is required for each database that contains primary data or for each database where replicated stored procedures are executed.

In Adaptive Server Enterprise, an embedded Replication Agent is provided with the database management system software. The Replication Agent for ASE is called RepAgent, and it is an Adaptive Server thread.

For non-ASE data servers, SAP provides these Replication Agent products:

Replication Agent for DB2 UDB – provides primary data server support for IBM DB2 UDB servers that run on IBM z/OS platforms.

Replication Agent – provides primary data server support for DB2 UDB, Microsoft SQL Server, and Oracle data servers that run on Linux, UNIX, or Microsoft Windows platforms.

Replication Agents read the primary database transaction log. The primary Replication Server reconstructs the transaction and forwards it to replicate sites that have subscriptions for the data.

Replication Server

The Replication Server at each primary or replicate site coordinates data replication activities for local data servers and exchanges data with Replication Servers at other sites.

Replication Server provides guaranteed delivery of transactions to each replicate site by:

Receiving transactions from primary databases through a Replication Agent and distributing them to replicate database sites that have subscriptions for the data

Receiving transactions from other Replication Servers and applying them to local replicate databases or forwarding them to other replication servers that have subscriptions for the data

Receiving requests for data updates from a replicate database and applies them to a primary database

The information needed to accomplish these tasks is stored in Replication Server system tables that are stored in the Replication Server System Database.

Replicate Data Server

Replicate data server manages a database that contains replicate data, which is data that is a “copy” of the data in a primary database.

Replication Server maintains the data in a replicate data server by logging in as a database user. In the case of non-ASE data servers, Replication Server logs in to the replicate data server through a database gateway server or directly to the data server.

Replication Server can treat any server as a data server if it supports a set of required data operations and transaction processing directives, either directly (such as Adaptive Server Enterprise) or indirectly (such as a Enterprise Connect Data Access database gateway server).

Supported Replicate Database Servers

SAP replication technology supports transaction replication in different relational database servers.

The relational database servers include:

v  SAP HANA database

v  IBM DB2 UDB on z/OS

v  IBM DB2 UDB on UNIX/Windows

v  Microsoft SQL Server

v  Oracle

v  SAP IQ