1WD_KEEPALIVE(8) System Manager's Manual WD_KEEPALIVE(8)
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6 wd_keepalive - a simplified software watchdog daemon
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9 wd_keepalive [-c filename|--config-file filename]
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12 This is a simplified version of the watchdog daemon. Unlike the full
13 watchdog, this daemon run no tests and only serves to keep the hardware
14 timer refreshed. Typically this is used on system start-up to provide
15 protection before the services that the full version tests are running,
16 and on shutdown to continue the refresh while those services are
17 stopped.
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19 If configured so it only opens /dev/watchdog, and keeps writing to it
20 often enough to keep the kernel from resetting, at least once per
21 minute. Each write delays the reboot time another minute. After a
22 minute of inactivity the watchdog hardware will cause a reset. In the
23 case of the software watchdog the ability to reboot will depend on the
24 state of the machines and interrupts.
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26 The wd_keepalive daemon can be stopped without causing a reboot if the
27 device /dev/watchdog is closed correctly, unless your kernel is com‐
28 piled with the CONFIG_WATCHDOG_NOWAYOUT option enabled.
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30 Under high system load wd_keepalive might be swapped out of memory and
31 may fail to make it back in in time. Under these circumstances the
32 Linux kernel will reset the machine. To make sure you won't get unnec‐
33 essary reboots make sure you have the variable realtime set to yes in
34 the configuration file watchdog.conf. This adds real time support to
35 wd_keepalive: it will lock itself into memory and there should be no
36 problem even under the highest of loads.
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38 On system running out of memory the kernel will try to free enough mem‐
39 ory by killing process. The wd_keepalive daemon itself is exempted from
40 this so-called out-of-memory killer.
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43 Available command line options are the following:
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45 -c config-file, --config-file config-file
46 Use config-file as the configuration file instead of the default
47 /etc/watchdog.conf.
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49 -X num, --loop-exit num
50 Run for 'num' loops then exit as if SIG_TERM was received.
51 Intended for test/debug (e.g. using valgrind for checking memory
52 access). If the daemon exits on a loop counter and you have the
53 CONFIG_WATCHDOG_NOWAYOUT option compiled for the kernel or
54 device-driver then an unplanned reboot will follow - be warned!
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57 /dev/watchdog
58 The watchdog device.
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60 /var/run/wd_keepalive.pid
61 The pid file of the running wd_keepalive.
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64 watchdog.conf(5)
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66 watchdog(8)
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704th Berkeley Distribution June 2015 WD_KEEPALIVE(8)