Replication is a process of maintaining a defined set of data in more than one location. It involves copying designated changes from one location (a source) to another (a target), and synchronizing the data in both locations. The source and target can be in logical servers (such as a DB2 database or a DB2 for OS/390 subsystem or data-sharing group) that are on the same machine or on different machines in a distributed network.
A number of IBM products enable you to replicate data. The product that is the focus of this book--DB2 DataPropagator--is a replication product for relational data. You can use it to replicate changes between any DB2 relational databases. You can also use it with other IBM products (such as DB2 DataJoiner and DataPropagator NonRelational) or non-IBM products (such as Microsoft SQL Server and Sybase SQL Server) to replicate data between a growing number of database products--both relational and nonrelational.
The replication environment that you need depends on when you want data updated and how you want transactions handled. The solution that's right for you might have a log-based or a trigger-based change-capture mechanism, or both. You also have the flexibility to choose the locations of the replication components to maximize the efficiency of your replication environment.
Before you go to Chapter 2 and begin designing your replication environment, read this chapter to familiarize yourself with the DB2 replication components and their associated concepts.