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The Veritas Cluster Server (VCS) package, provided as part of the installation of SF Oracle RAC, provides the ability to automate the entire Oracle RAC environment. For example, VCS can be used to automatically start the Cluster Volume Manager and Cluster File System resources within the cluster, bring up IP addresses and the Oracle Listener, mount the file systems with the Oracle binaries, mount the storage for the database instances, and actually start the database instance. Placing the database under VCS control in no way removes the DBA's capability for full control. It simply automates actions to enable the cluster to start up after any outage.
In an SF Oracle RAC cluster, the administrative staff is free to choose how much, or how little automated control they desire. Less automation means more traditional hands-on interaction, but also requires the administrator take corrective action in more circumstances. A better idea may be to allow VCS complete startup control to take care of system and power failures and restarts, while still allowing manual control if necessary.
VCS uses installed agents to manage the resources in the SF Oracle RAC environment. Each type of resource has an agent; for example, VCS uses a CFSMount agent for mounting shared file systems, the CVMVolDg agent for activating shared disk groups and monitoring shared volumes, an Oracle agent for starting the Oracle database, an IP agent for setting up and monitoring an IP address, and so on.
The VCS configuration file (/etc/VRTSvcs/conf/config/main.cf) contains the information the agents require to manage each resource in the environment. In addition, the configuration file specifies the dependencies between resources; the dependencies that one resource has upon another sets the order in which the resources are started or stopped by the agents.
Within VCS configurations, resources exist in service groups. A service group consists of resources that must function together in support of a service. For example, an Oracle service group can consist of the Oracle database, a CFSMount resource for the shared file system containing the database, and a CVMVolDg resource for the shared disk group that contains the file system. Just as resources have dependencies upon other resources, service groups can have dependencies on other service groups.