SMF Components

SMF includes a master restarter daemon and delegated restarters. In addition, each service or service instance can store configuration data in properties. These properties are organized into property groups to make administration simpler.

SMF Master Restarter Daemon

The svc.startd daemon is the master process starter and restarter. The daemon is responsible for managing service dependencies for the entire system. The daemon takes on the previous responsibility that init held of starting the appropriate /etc/rc*.d scripts at the appropriate run levels. First, svc.startd retrieves the information in the service configuration repository. Next, the daemon starts services when their dependencies are met. The daemon is also responsible for restarting services that have failed and for shutting down services whose dependencies are no longer satisfied. The daemon uses operating system events, such as process death, to keep track of service states.

SMF Delegated Restarters

Some services have a set of common behaviors on startup. To provide commonality among these services, a delegated restarter might take responsibility for these services. In addition, a delegated restarter can be used to provide more complex or application-specific restarting behavior. The delegated restarter can support a different set of methods, but exports the same service states as the master restarter. The restarter's name is stored with the service. A current example of a delegated restarter is inetd, which can start Internet services on demand, rather than having the services always running. The defined restarter for each service can be displayed using the svcs -l command.

SMF Properties and Property Groups

All information in the service configuration repository is stored as a set of properties, which are grouped by property groups. Property groups are used to group different types of service information. Property groups can be applied to the system as well as to individual services. Some of the common system-defined property groups include:

• general – Contains information about the service instance, including the general/enabled property, which defines whether the instance is enabled

• restarter – Contains runtime information that is stored by the service's restarter, including the restarter/state property, which shows the current state of the service

• start – Contains the start method definition, including the start/exec property, which defines what program to execute to start the service

Another common property group is config. The config property group is not system defined, so it can be used by services developers to hold service data. See the smf(5) man page for more information about properties and property groups.