sac(1M) sac(1M)
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 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; 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.
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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 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 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
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 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
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/var/saf/log
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