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® for i licensed program number, provides several interfaces to configure and manage high-availability solutions and technology. The
PowerHA
licensed program provides
the following interfaces: - High Availability Solutions Manager graphical interface
- This graphical interface allows you to select from several IBM i supported
high-availability solutions. This interface validates all technology
requirements for your selected solution, configures your selected
solution and the associated technologies and provides simplified management
of all the high availability technologies that comprise your solution.
- Cluster Resource Services graphical interface
- This graphical interface provides an experienced user more flexibility in customizing a high availability-solution. It allows you to configure and manage cluster technologies, such as CRGs. You can also configure some independent disk pools from this interface when they are used as part of a high availability solution.
- IBM PowerHA for i commands
- These commands provide similar functions but are available through a command-line interface.
- APIs
- These IBM PowerHA for i APIs allow you to work with new function
for independent disk pools.
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.