sac(1M) MISC. REFERENCE MANUAL PAGES 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 environ-
ment. When sac is invoked, it first looks for the per-
system configuration script /etc/saf/sysconfig. sac inter-
prets 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 mon-
itor 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.
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sac(1M) MISC. REFERENCE MANUAL PAGES sac(1M)
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. STOP-
PING 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 moni-
tor 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
Last change: Essential Utilities 2