Replication Strategies: Data Migration, Distribution and Synchronization
Replication Server provides a safe way to upgrade or migrate existing systems and platforms. By replicating data during migrations, customers can migrate existing database data without interrupting critical business applications. The applications can be switched to the new version or platform once the new database server is populated, applications are tested, and any new features are implemented.
Replication Server also supports replicating data to and from non-Sybase data servers. Data can be replicated to non-Sybase data servers such as Oracle, Informix, IBM DB2, and Microsoft SQL Server using Sybase DirectConnect™ gateways. Transactions can be captured and forwarded from non-Sybase data servers using Sybase Replication Agents™. Data can also be replicated from a non-Sybase source, through Replication Server to a non-Sybase destination.
Replication Server provides warm standby capability with a pair of databases, one as the active database and one as the standby database, is supported by Replication Server functionality. As clients update the active database, Replication Server copies transactions to the standby database, maintaining consistency between the two. Should the active database fail for any reason, you can switch to the standby database, making it the active database, and resume operations with little interruption.
Using a reliable store and forward technology, Replication Server accommodates the reality that architecture changes occur, and network connections and network components can fail. If a remote site is accessible, the information is forwarded to that site; if one or more remote sites become unavailable, the information is stored until the connections are re-established, at which point copies are automatically resynchronized. Corporate sites can continue operations using their local copy of the data even when remote sites are inaccessible.
Critical to making such a distributed environment easily manageable is the Replication Server Manager™, a powerful systems management tool with an easy to use graphical user interface. Available at no extra charge with Replication Server, this systems management tool allows administrators to manage and monitor from a single site all distributed components of the enterprise client/server replication environment. This paper begins with an introduction to the concept of data replication for distributed applications with examples of configurations supported by Replication Server.We then discuss the business and technical problems that such configurations solve. Next, we describe in detail how Replication Server works with emphasis on the benefits of the Sybase architecture. The Appendix to this paper describes in detail what needs to happen at each site when a replication system is put together.