Types of Resources and Agent Entry Points They Require

Different types of resources require different types of control, requiring implementation of different entry points. Resources can be classified as OnOff, OnOnly, or Persistent, depending on the entry points required to control them.

• OnOff resources

Most resources are OnOff, meaning VCS starts and stops them as required. For example, VCS assigns the IP address to the specified NIC and removes the assigned IP address when the associated service group is taken offline. Another example is the DiskGroup resource. VCS imports a disk group when needed and deports it when it is no longer needed. For agents of OnOff resources, all entry points can be implemented.

• OnOnly resources

An OnOnly resource is brought online when required by VCS, but it is not taken offline when the associated service group is taken offline. For example, in the case of the FileOnOnly resource, VCS creates the specified file if required, but does not delete the file if the associated service group is taken offline. For agents of OnOnly resources, online and monitor entry points can be implemented.

• Persistent resources

A Persistent resource cannot be brought online or taken offline, yet VCS requires the resource to be present in the configuration. For example, a NIC resource cannot be started or stopped, but it is required to configure an IP address. VCS monitors Persistent resources to ensure their status and operation. An agent for a Persistent resource requires the monitor entry point.

For all these types of resources, info and action entry points can be implemented.