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What can be done with the systemd watchdog?
Systemd’s watchdog can be mainly used for 3 different actions: hardware reset (leveraging the CPU hardware watchdog exposed at /dev/watchdog). This is enabled by the RuntimeWatchdogSec= option in /etc/systemd/system.conf system reset as a fallback measure in response to multiple unsuccessful application resets. Also defined in the systemd unit
When to start watchdog when network is available?
To start the watchdog when network is available see the Systemd section below. watchdog can run an external command for user-defined tests. A return code not equal 0 means an error occured and watchdog should react. If the external command is killed by an uncaught signal this is considered an error by watchdog too.
What can the Linux watchdog daemon be used for?
The Linux watchdog daemon should be used for system reset jobs, though it can also run a “repair binary” on persistent errors that could be used to fix or restart a process.
Is the hardware watchdog driver disabled in Linux?
All checks are executed and the results are logged as usual, but no action is taken. Also your hardware card or the kernel software watchdog driver is not enabled. Temperature checking is also disabled since this triggers the hardware watchdog on some cards.
How to use suspend and hibernate in Arch Linux?
systemd provides native commands for suspend, hibernate and a hybrid suspend, see Power management#Power management with systemd for details. This is the default interface used in Arch Linux. See Power management#Sleep hooks for additional information on configuring suspend/hibernate hooks.
How does suspend to disk work on a computer?
Suspend to disk method saves the machine’s state into swap space and completely powers off the machine. When the machine is powered on, the state is restored. Until then, there is zero power consumption. Suspend to both method saves the machine’s state into swap space, but does not power off the machine.
How does watchdog keep the kernel from resetting?
If the daemon stops doing that, the system is reset. watchdog is such a daemon. It opens /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 the reset.
When to use watchdog shutdown timer in system shutdown?
Or rather I should say your reboot. As the manual page specifically notes, the watchdog shutdown timer only applies to reboots, not to powering the system off. (One consequence of what ShutdownWatchdogSec does and doesn’t cover is that for most systems it’s safe to set it to a very low timeout.
How to not restart a systemd service, when the…?
@BoyanAtanasov That’s not how systemd works, it will not restart services that require Postgres if you restart Postgres. It is possible that one or more of the services that depend on it are exiting once it goes down, in which case systemd will bring them up again if configured to do so.