application on the takeover node when a fallover occurs. For more information about creating application server resources, see the HACMP for AIX, Version 4.3: Installation Guide,
2.5.1 Performance Requirements
In order to plan your application’s needs, you must have a thorough understanding of it. One part of that is to have The Application Planning Worksheets, found in Appendix A of the HACMP for AIX Planning Guide,
Your applications have to be served correctly in an HACMP cluster environment. Therefore, you need to know not only how they run on a single uni- or multiprocessor machine, but also which resources are required by them. How much disk space is required, what is the usual and critical load the application puts on a server, and how users access the application are some critical factors that will influence your decisions on how to plan the cluster.
Within an HACMP environment there are always a number of possible states in which the cluster could be. Under normal conditions, the load is serviced by a cluster node that was designed for this application’s needs. In case of a failover, another node has to handle its own work plus the application it is going to take over from a failing node. You can even plan one cluster node to be the takeover node for multiple nodes; so, when any one of its primary nodes fail, it has to take over its application and its load. Therefore, the performance requirements of any cluster application have to be understood in order to have the computing power available for
2.5.2 Application Startup and Shutdown Routines
Highly available applications do not only have to come up at boot time, or when someone is starting them up, but also when a critical resource fails and has to be taken over by another cluster node. In this case, there have to be robust scripts to both start up and shut down the application on the cluster nodes. The startup script especially must be able to recover the application from an abnormal termination, such as a power failure. You should verify that it runs properly in a uniprocessor environment before including the HACMP for AIX software.
