Finding the reason of a force shutdown of a VM

Question

We have a linux VM running under XenServer that reboots itself with no apparent reason. Checking the /var/log files in Xen we noticed that it's sending a force shutdown to the VM, like this:

messages:Dec 6 15:01:07 XenSrvDell2 BLKTAP-DAEMON[7309]: /local/domain/0/backend/tap/19/51728: got start/shutdown watch on /local/domain/0/backend/tap/19/51728/tapdisk-request

What we can't find is the reason why the force-shutdown was initiated. Is there any "higher level log" that might tell us who or why triggered the shutdown?

Answer 1

It could happen if Dom0 runs out of memory and starts crashing for example. Or if there was a device in dispute - shared for writing by multiple machines - but I guess that these are not the circumstances here. Let's hope nobody hacked your box and is playing with you. Or maybe some kind of simple watchdog/heartbeat sensor reseting your machine because it failed to report. In general more information could shed more light on this.