Resources, Resource Groups, and Resource Types (5/02)

Data services utilize several types of resources: applications such as Apache Web Server or iPlanet Web Server utilize network addresses (logical hostnames and shared addresses) upon which the applications depend. Application and network resources form a basic unit that is managed by the RGM.

Data services are resource types. For example, Sun Cluster HA for Oracle is the resource type SUNW.oracle-server and Sun Cluster HA for Apache is the resource type SUNW.apache.

A resource is an instantiation of a resource type that is defined cluster wide. There are several resource types defined.

Network resources are either SUNW.LogicalHostname or SUNW.SharedAddress resource types. These two resource types are pre-registered by the Sun Cluster software.

The HAStorage and HAStoragePlus resource types are used to synchronize the startup of resources and disk device groups upon which the resources depend. It ensures that before a data service starts, the paths to cluster file system mount points, global devices, and device group names are available. For more information, see "Synchronizing the Startups Between Resource Groups and Disk Device Groups" in the Sun Cluster 3.0 12/01 Data Services Installation and Configuration Guide. (The HAStoragePlus resource type became available in Sun Cluster 3.0 5/02 and added another feature, enabling local file systems to be highly available. For more information on this feature, see "Enabling Highly Available Local File Systems".)

RGM-managed resources are placed into groups, called resource groups, so that they can be managed as a unit. A resource group is migrated as a unit if a failover or switchover is initiated on the resource group.

When you bring a resource group containing application resources online, the application is started. The data service start method waits until the application is up and running before exiting successfully. The determination of when the application is up and running is accomplished the same way the data service fault monitor determines that a data service is serving clients. Refer to the Sun Cluster 3.0 12/01 Data Services Installation and Configuration Guide for more information on this process.