>On Tuesday 03 August 2004 12:40 pm, Mikkel L. Ellertson wrote:
The device you are talking about is a watchdog timer. They are available for a lot of different systems. You can get one on a ISA
or PCI card for a PC as well. They used to be built-in on the
Sparc Stations. There is support for them in the Linux kernel.
For anything that a cron job reboot would work for, the software
watchdog module for the kernel should also handle. I am not sure
how it would handle a kernel panic. You need the hardware version
to handle a hardware lockup.
Neither am I. I did do some looking around because it should be theoretically possible to trigger an UPS to cut and then restart power to its devices which would force a hard reboot to a locked machine but I never found anything other than the device I mentioned for Mac's and those were limited to their software since they have to tie in and monitor a specific process.
I might look into it a little more because, although my own server is not really critical, I would like to have something that would force the reboot if it locks hard.
I imagine that it wouldn't be too difficult, you could simply run an agent to send a report to the device, if the report doesn't arrive, it forces a reboot but it would need to be factored into the power supply and if you use a UPS, that might be problematic.
I am not sure about the one for the Mac, but the one for the PC generates a NMI or a reset if it times out. The way they usualy work is you have to write to a specific port or memory location before the timer times out, or it reboots the system. So the system will reset if it get hung. The software version is not as powerfull. But you can read about more about both type. Read watchdog.txt in the Documentation directory of the kernel source, or kernel docs.
Mikkel --
Do not meddle in the affairs of dragons, for you are crunchy and taste good with Ketchup!
____________________________________________________ Want to buy your Pack or Services from MandrakeSoft? Go to http://www.mandrakestore.com Join the Club : http://www.mandrakeclub.com ____________________________________________________
