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wdmd(8) [centos man page]

WDMD(8) 						      System Manager's Manual							   WDMD(8)

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, other- wise 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)

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WD_KEEPALIVE(8) 					      System Manager's Manual						   WD_KEEPALIVE(8)

NAME
wd_keepalive - a simplified software watchdog daemon SYNOPSIS
wd_keepalive [-c filename|--config-file filename] DESCRIPTION
This is a simplified version of the watchdog daemon. If configured so it only opens .IR /dev/watchdog , and keeps writing to it often enough to keep the kernel from resetting, at least once per minute. Each write delays the reboot time another minute. After a minute of inactivity the watchdog hardware will cause a reset. In the case of the software watchdog the ability to reboot will depend on the state of the machines and interrupts. The wd_keepalive daemon can be stopped without causing a reboot if the device /dev/watchdog is closed correctly, unless your kernel is com- piled with the CONFIG_WATCHDOG_NOWAYOUT option enabled. Under high system load wd_keepalive might be swapped out of memory and may fail to make it back in in time. Under these circumstances the Linux kernel will reset the machine. To make sure you won't get unnecessary reboots make sure you have the variable realtime set to yes in the configuration file watchdog.conf. This adds real time support to wd_keepalive: it will lock itself into memory and there should be no problem even under the highest of loads. On system running out of memory the kernel will try to free enough memory by killing process. The wd_keepalive daemon itself is exempted from this so-called out-of-memory killer. OPTIONS
Available command line options are the following: -c config-file, --config-file config-file Use config-file as the configuration file instead of the default /etc/watchdog.conf. FILES
/dev/watchdog The watchdog device. /var/run/wd_keepalive.pid The pid file of the running wd_keepalive. SEE ALSO
watchdog.conf(5) watchdog(8) 4th Berkeley Distribution January 2005 WD_KEEPALIVE(8)
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