Creating a two-server active-passive high availability configuration

You can provide a basic level of high availability by configuring the IBM® InfoSphere® Information Server software tiers in an active-passive high availability configuration.

In a two-server active-passive high availability configuration, two computers share a storage device. The metadata repository tier, engine tier, and services tier are all installed on the shared storage device. One of the computers (the active server) hosts the tiers. The other computer (the passive server) is started, but is not running any tier software. A high availability software product is installed on both servers, such as IBM Tivoli® System Automation for Multiplatforms on Linux® or UNIX systems or Microsoft Cluster Service (MSCS) on Microsoft Windows systems. The high availability software maintains a heartbeat, which is a periodic signal from the active server to the passive server that indicates that the active server is operational. If the active server fails, the heartbeat also fails. The high availability software restarts all the services on the passive server. This process is called a failover.

With this configuration, a floating IP address and virtual host name are defined for the server pair. This information is associated with the active server. All client programs connect to the server by using this address or host name. If the active server fails, the floating IP address and virtual host name are automatically reassociated with the passive server.

If you provide high availability for the services tier or metadata repository tier (or both) by using other methods, you can choose to include only the remaining tiers in the active-passive configuration. For example, you might choose to implement an IBM WebSphere® Application Server cluster for your services tier and an IBM Db2® Database for Linux, UNIX, and Windows cluster for your metadata repository tier. In this case, the servers in your active-passive configuration host only the engine tier.

To set up a high availability configuration, you must have a solid understanding of network technologies such as protocols, layers, and devices. Highly available configurations, especially configurations that involve clustering, are technically complex and require expertise to implement them successfully.