Sun Cluster 3.1 Data Services Developer's Guide

Overview of the Sample Data Service

The sample data service starts, stops, restarts and switches the DNS application among the nodes of the cluster in response to cluster events such as administrative action, application failure, or node failure.

Application restart is managed by the Process Monitor Facility (PMF). If application deaths exceed the failure count within the failure time window, the fault monitor fails the resource group containing the application resource over to another node.

The sample data service provides fault monitoring in the form of a PROBE method. that uses the nslookup command to ensure that the application is healthy. If the probe detects a hung DNS service, it tries to correct the situation by restarting the DNS application locally. If this does not improve the situation and the probe repeatedly detects problems with the service, then the probe attempts to fail over the service to another node in the cluster.

Specifically, the sample data service includes: