Sun Cluster Data Services Developer's Guide for Solaris OS

Sun Cluster Application Environment

The Sun Cluster system enables applications to be run and administered as highly available and scalable resources. The Resource Group Manager (RGM) provides the mechanism for high availability and scalability. The following elements form the programming interface to this facility:

The following figure shows the interrelationship of these elements.

Figure 1–1 Programming Architecture of the Sun Cluster Application Environment

Diagram showing interrelationship between callback methods, RMAPI,
Process Monitor Facility (PMF), and DSDL

SunPlex Agent Builder, which is described in Chapter 9, SunPlex Agent Builder, is a tool in the Sun Cluster package that automates the process of creating a data service. Agent Builder generates data service code in either C (by using DSDL functions to write the callback methods) or in the Korn (ksh) shell command language (by using low-level API commands to write the callback methods).

The RGM runs as a daemon on each cluster node and automatically starts and stops resources on selected nodes according to preconfigured policies. The RGM makes a resource highly available in the event of a node failure or reboot by stopping the resource on the affected node and starting it on another node. The RGM also automatically starts and stops resource-specific monitors. These monitors detect resource failures and relocate failing resources onto other nodes or monitor other aspects of resource performance.

The RGM supports both failover resources, which can be online on only one node at a time, and scalable resources, which can be online on multiple nodes simultaneously.