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SAP Sybase SQL Anywhere 16.0 » SQL Anywhere Server - Database Administration » High availability and read-only scale-out systems » Database mirroring

 

Tutorial: Creating a database mirroring system with multiple databases that share an arbiter server

In this configuration, the primary and mirror servers each host three individual databases participating in mirroring systems. All three mirroring systems communicate with the same arbiter server. Each mirroring system uses unique alternate server names that are specified using the PRIMARY and MIRROR clauses of the CREATE MIRROR SERVER statement. With this type of configuration, the primary, mirror, and arbiter servers can all run on separate computers.

Diagram showing the mirroring system.

If the primary server becomes unavailable, then a role switch occurs and the mirror server takes ownership of the databases, becoming the primary server. The client must re-establish a connection to the new primary server. The alternate server name is all that must be specified to re-establish the connection to the primary server. This configuration also has the ability to protect against failure of a single database. If a database running on the primary server becomes unavailable, then a role switch occurs and the mirror server takes ownership of the failed database. The mirror server becomes the primary server for only this database. The client must re-establish a connection to the primary server for this database using the alternate server name.

Note

In this tutorial, all the database servers are running on the same computer. However, each database server must be installed on a separate computer in a production environment.

If this tutorial is used with database servers running on different computers, references to localhost in the connection strings must be changed to the actual computer names.

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Lesson 1: Creating a database mirroring system with three databases and one arbiter server
Lesson 2: Using and testing the database mirroring system