shutdown does not complete

[Jörn Clausen <joernc%googlemail.com@localhost>]

I have two HP ProLiant servers running NetBSD/amd64, and more often
than I like, shutting them down does not complete.

The console shows

syncing disks... 3 3 1 done

and then nothing happens. There is no longer a prompt, but the kernel
still reacts to e.g. connecting and disconnecting USB devices or
pressing the power button ("power button pressed, shutting down!",
though nothing happens).

One of the machines has two data disks (i.e. not including the root
filesystem) as RAID1 and seems to be more prone to the problem, but
from time to time the other machine hangs in the same way.

All I can do is press the power button for five seconds to force a
power-off. Both machines are currently running 7.0.1, but they showed
the same behaviour under 6.1.5.

Any ideas what causes this problem and how to avoid it?

-- 
Joern Clausen
http://www.oe-files.de/photography/