How a Warm Standby Works

Learn how a warm standby works.

This figure illustrates the normal operation of an example warm standby application.

Warm Standby Application—Normal Operation
Figure 3-1 illustrates the normal operation of an example warm standby application where the client executes transactions in the active database. The Replication Server executes the transactions in the standby database and may also copy transactions to destination databases and remote Replication Servers.

Figure 3-1 illustrates the normal operation of an example warm standby application where the client executes transactions in the active database. The Replication Server executes the transactions in the standby database and may also copy transactions to destination databases and remote Replication Servers.

In this warm standby application:

Client applications execute transactions in the active database.
The RepAgent for the active database retrieves transactions from the transaction log and forwards them to Replication Server.
Replication Server executes the transactions in the standby database.
Replication Server may also copy transactions to destination databases and remote Replication Servers.

Warm Standby Application Example—Before Switching

Figure 3-4 illustrates a warm standby application for a database that does not participate in the replication system other than through the activities of the warm standby application itself. This also illustrates a warm standby application in normal operation before you switch the active and standby databases. The Replication Server writes transactions received from the active database into an inbound message queue. This inbound queue is read by the D S I thread for the standby database, which executes the transactions in the standby database. Transactions in this figure are simply replicated from the active database into the standby database.

This figure shows details about the components and processes in a warm standby application.