Re: [Sheflug] Software watchdog

["Chris J/#6" <nospam [at] nccnet.co.uk>]

> Hi,
> 	We have a couple of web servers running nicely and happily
> churning PHP/MySQL queries around. Because I maintain them, and I enjoy
> going on holidays and basically forgetting about this, I was thinking of
> ways to make my life easier.
> 
> 	It would be nice to have some sort of software watchdog
> implemented in the kernel that would reset the computer if anything went
> wrong. If the box was to crash and get locked without rebooting, we
> would get a considerable amount of downtime. If it reboots, then fine.
> 

You mean like this (in Kernel 2.2.19, make xconfig -> Character Devices) ?

---------------------------------------------------------------------
CONFIG_WATCHDOG:

If you say Y here (and to one of the following options) and create a
character special file /dev/watchdog with major number 10 and minor
number 130 using mknod ("man mknod"), you will get a watchdog, i.e.:
subsequently opening the file and then failing to write to it for
longer than 1 minute will result in rebooting the machine. This
could be useful for a networked machine that needs to come back
online as fast as possible after a lock-up. There's both a watchdog
implementation entirely in software (which can sometimes fail to
reboot the machine) and a driver for hardware watchdog boards, which
are more robust and can also keep track of the temperature inside
your computer. For details, read Documentation/watchdog.txt in the
kernel source.

The watchdog is usually used together with the watchdog daemon which is
available via FTP (user: anonymous) from
ftp://metalab.unc.edu/pub/linux/system/daemons/watchdog. This daemon can
check a larger part of the system. For instance it can monitor NFS
connections and reboot the machine when the process table is full or the
workload exceeds a predefined value.

If unsure, say N.

-------------------------------------------------------------------

HTH :)

Chris...


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