If an application becomes unavailable, HACMP tries to restart the application on the primary cluster
node three times. In general, if the application does not start after three attempts, HACMP starts the
application on the takeover node to continue service.
Available fallover configurations
HACMP Smart Assist for WebSphere resource components support several high availability fallover
configurations.
These configurations include:
v Hot standby.
In a hot standby configuration, one node performs the work while the other node waits as a fallover
location.
v Mutual takeover.
In a mutual takeover configuration, each node runs an application while also providing a fallover
location for the application of the other node.
v Multiple nodes.
Configuration of three or more nodes in which one node provides a fallover location for the
applications running on the other nodes in the cluster.
For a comparison of the different fallover configurations available for each application supported by
HACMP Smart Assist for WebSphere, see the following table:
Table 1. Different fallover configurations
Component to Keep Highly Available Hot Standby Mutual Takeover Multiple Node
IBM HTTP Server X X X
WebSphere Application Server Node X X X
WebSphere Application Server Deployment Manager X X X
Tivoli Directory Services X
WebSphere Application Server Cluster Transaction Log X
Configuring HACMP with HACMP Smart Assist for WebSphere
HACMP Smart Assist for WebSphere sets up your HACMP resource configuration for you. It gathers
information from the application configuration, the system configuration, and from you, and creates an
HACMP resource group to protect a specified application.
An HACMP resource group contains a set of resources, such as cluster nodes, volume groups, and IP
labels (used by server applications to communicate with clients) that HACMP manages as a unit.
Note: The term application server can have different meanings. A WebSphere Application Server makes
Web-based applications available to users. An HACMP application server identifies the application start
and stop scripts that are used in conjunction with HACMP.
In addition to creating a resource group for each application to be made highly available, HACMP Smart
Assist for WebSphere performs the following tasks:
v Creates an HACMP application server for the application
v Ensures the application has a service IP label that can be transferred to another system, thus keeping
the application highly available
v Creates HACMP application monitors to detect failures in application processes
v Provides start and stop scripts for the application (that is, application servers)
v Stores the generated HACMP configuration in the HACMP configuration database (ODM).
2 High Availability Cluster Multi-Processing for AIX: Smart Assist for WebSphere User's Guide
