Making application programs resilient

Learn how to make application programs resilient.

A resilient application is expected to have the following characteristics:

• The application can be restarted on this node or another node
• The application is accessible to the client through the IP address
• The application is stateless or state information is known
• Data that is associated with the application is available after switchover

The three essential elements that make an application resilient to system outages in a clustered environment are:

The application itself

How tolerant is the application to errors or to system outages, and how transparently can the application restart itself?

The application can handle this through the use of clustering capabilities.

Associated data

When an outage occurs, does it affect the availability of any associated data?

You can store critical data in switched disks which allow data to remain available during an outage. Alternatively, a cluster middleware IBM® Business Partner replication product that takes advantage of the clustering capabilities can handle this.

Control capabilities and administration

How easy is it to define the environment that supports the availability of the data and the application?

IBM PowerHA® SystemMirror® for i licensed program provides several interfaces to configure and manage high-availability solutions and technology.

In addition, you can also use a third-party cluster management interface that uses the clustering APIs and also combines resilient applications with resilient data can handle this.