NAME

sac - service access controller

SYNOPSIS

sac -t sanity_interval

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 looks for the per-system configuration script /etc/saf/_sysconfig. sac interprets _sysconfig to customize its own environment. The modifications 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 [fork(2)] and creates a utmp entry with the type field set to LOGIN_PROCESS. 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; 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 monitors 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 Controller 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:

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 running.

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  with  -k.)   This is the normal ``not run-
          ning'' 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 monitored 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  moni-
     tors  and  takes  the  appropriate  action.  The SAC is
     responsible for  restarting  port  monitors  that  ter-
     minate.   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 monitor was added by sacadm; this information is included in /etc/saf/pmtag/_sactab

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

SEE ALSO

sacadm(1M), pmadm(1M).

FILES

/etc/saf/_sactab
/etc/saf/_sysconfig
/var/adm/utmp
/var/saf/_log