NAME

       wdmd - watchdog multiplexing daemon

SYNOPSIS

       wdmd [OPTIONS]

DESCRIPTION

       This  daemon  opens  /dev/watchdog  and  allows multiple independent sources to detmermine
       whether each KEEPALIVE is done.  Every test interval (10 seconds), the daemon  tests  each
       source.   If  any test fails, the KEEPALIVE is not done.  In a standard configuration, the
       watchdog timer will reset the system if  no  KEEPALIVE  is  done  for  60  seconds  ("fire
       timeout").   This  means  that  if a single test fails 5-6 times in row, the watchdog will
       fire and reset the system.  With multiple test sources, fewer separate  failures  back  to
       back can also cause a reset, e.g.

       T seconds, P pass, F fail
       T00: test1 P, test2 P, test3 P: KEEPALIVE done
       T10: test1 F, test2 F, test3 P: KEEPALIVE skipped
       T20: test1 F, test2 P, test3 P: KEEPALIVE skipped
       T30: test1 P, test2 F, test3 P: KEEPALIVE skipped
       T40: test1 P, test2 P, test3 F: KEEPALIVE skipped
       T50: test1 F, test2 F, test3 P: KEEPALIVE skipped
       T60: test1 P, test2 F, test3 P: KEEPALIVE skipped
       T60: watchdog fires, system resets

       (Depending  on timings, the system may be reset sometime shortly before T60, and the tests
       at T60 would not be run.)

       A crucial aspect to the design and function of wdmd is that if any single source does  not
       pass tests for the fire timeout, the watchdog is guaranteed to fire, regardless of whether
       other sources on the system have passed or failed.  A spurious reset due to  the  combined
       effects of multiple failing tests as shown above, is an accepted side effect.

       The  wdmd  init  script  will load the softdog module if no other watchdog module has been
       loaded.

       wdmd cannot be used on the system with any other program that needs to open /dev/watchdog,
       e.g. watchdog(8).

   Test Source: clients
       Using  libwdmd,  programs  connect to wdmd via a unix socket, and send regular messages to
       wdmd to update an expiry time for their connection.  Every test interval, wdmd will  check
       if  the  expiry  time  for a connection has been reached.  If so, the test for that client
       fails.

   Test Source: scripts
       wdmd will run scripts from a designated directory every test interval.  If a script  exits
       with  0, the test is considered a success, otherwise a failure.  If a script does not exit
       by the end of the test interval, it is considered a failure.

OPTIONS

       --version, -V
                Print version.

       --help, -h
                Print usage.

       --dump, -d
                Print debug information from the daemon.

       --probe, -p
                Print path of functional watchdog device.  Exit code 0 indicates a
                functional device was found.  Exit code 1 indicates a functional device
                was not found.

       -D
                Enable debugging to stderr and don't fork.

       -H 0|1
                Enable (1) or disable (0) high priority features such as realtime
                scheduling priority and mlockall.

       -G name
                Group ownership for the socket.

       -S 0|1
                Enable (1) or disable (0) script tests.

       -s path
                Path to scripts dir.

       -k num
                Kill unfinished scripts after num seconds.

       -w path
                The path to the watchdog device to try first.

                                            2011-08-01                                    WDMD(8)