sac(1M)                                                             sac(1M)

NAME
     sac - service access controller

SYNOPSIS
     sac -t sanityinterval

DESCRIPTION
     The Service Access Controller (SAC) is the overseer of the server
     machine. It is started when the server machine enters multiuser mode.
     The SAC performs several important functions as explained below.

     -  Customizing the SAC environment

        When sac is invoked, it first checks whether the per-system confi-
        guration script /etc/saf/sysconfig exists [see doconfig(3C)]. sac
        interprets sysconfig to customize its own environment. The modifi-
        cations made to the SAC environment by sysconfig are inherited by
        all the children of the SAC. This inherited environment may be
        modified by the children.

     -  Starting port monitors

        After it has interpreted the sysconfig file, the sac reads its
        administrative file /etc/saf/sactab. sactab specifies which port
        monitors are to be started. For each port monitor to be started,
        sac forks a child [see fork(2)] and creates a utmp entry with the
        type field set to LOGINPROCESS. Each child then interprets its
        per-port monitor configuration script /etc/saf/pmtag/config, if
        the file exists. These modifications to the environment affect the
        port monitor and will be inherited by all its children. Finally,
        the child process execs the port monitor, using the command found
        in the sactab entry. (See sacadm(1M); this is the command given
        with the -c option when the port monitor is added to the system.)

     -  Polling port monitors to detect failure

        The -t option sets the frequency with which sac polls the port mon-
        itors on the system. This time may also be thought of as half of
        the maximum latency required to detect that a port monitor has
        failed and that recovery action is necessary.

     -  Administrative functions

        The Service Access Controller represents the administrative point
        of control for port monitors. Its administrative tasks are
        explained below.

     When queried (sacadm with either -l or -L), the Service Access Con-
     troller returns the status of the port monitors specified, which
     sacadm prints on the standard output. A port monitor may be in one of
     six states:




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sac(1M)                                                             sac(1M)

     ENABLED        The port monitor is currently running and is accepting
                    connections. See sacadm(1M) with the -e option.

     DISABLED       The port monitor is currently running and is not
                    accepting connections. See sacadm with the -d option,
                    and see NOTRUNNING, below.

     STARTING       The port monitor is in the process of starting up.
                    STARTING is an intermediate state on the way to ENABLED
                    or DISABLED.

     FAILED         The port monitor was unable to start and remain run-
                    ning.

     STOPPING       The port monitor has been manually terminated but has
                    not completed its shutdown procedure. STOPPING is an
                    intermediate state on the way to NOTRUNNING.

     NOTRUNNING     The port monitor is not currently running. (See
                    sacadm(1M) with -k.) This is the normal "not running"
                    state. When a port monitor is killed, all ports it was
                    monitoring are inaccessible. It is not possible for an
                    external user to tell whether a port is not being moni-
                    tored or the system is down. If the port monitor is not
                    killed but is in the DISABLED state, it may be possible
                    (depending on the port monitor being used) to write a
                    message on the inaccessible port telling the user who
                    is trying to access the port that it is disabled. This
                    is the advantage of having a DISABLED state as well as
                    the NOTRUNNING state.

     When a port monitor terminates, the SAC removes the utmp entry for
     that port monitor.

     The SAC receives all requests to enable, disable, start, or stop port
     monitors and takes the appropriate action.

     The SAC is responsible for restarting port monitors that terminate.
     Whether or not the SAC will restart a given port monitor depends on
     two things:

     -  the restart count specified for the port monitor when the port mon-
        itor was added by sacadm; this information is included in
        /etc/saf/pmtag/sactab;

     -  the number of times the port monitor has already been restarted.








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sac(1M)                                                             sac(1M)

FILES
     /etc/saf/sactab
     /etc/saf/sysconfig
     /var/saf/log
     /var/adm/utmp

SEE ALSO
     pmadm(1M), sacadm(1M), doconfig(3C).














































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