Company computer utilization?

[Michael Stein]

> Anyway, I do CFD on a cluster and am always looking for more resources,
> because there are never enough.  We have 100's of P4 and P4 Xeon boxes
> setting around running windows by day and idle by night.  It was suggested
> that we start utilizing these resources at night and I'd be happy to do
> this, except I need or at least prefer them to be linux.  Therefore, we need
> a way to auto reboot the boxes at some time in the evening to linux and then
> back to windows in the morning.  One of our IT folks is already working on
> this, but I thought someone out in beowulf land may already have this
> figured out, or know of some nifty software/freeware to handle this.  If
> anyone has any ideas/suggestions, etc. I'd appreciate it.  It has to be
> automatic because most of the users would probably not do anything as simple
> as reboot their computer when they go home.

I looked into doing this in a computer lab at one point but never
implemented it (the lab increased it's open hours). 

Keep in mind that a lab is easier since you know when it closes, look
out for someone staying late and working on their Windows system --
you don't want to shutdown their machine on top of them.  Perhaps
you could figure out a way to tell if the machine was unused (good
luck getting people to log out at night...).

My design assumed each lab machine had both NT and Linux installed on it
(the Linux partition could be minimal, with most of the system mounted
via NFS).

I had the normal "DOS" MBR boot sector and controlled which system
booted by changing the "active" partition in the boot sector.

This is trivial to change from Linux (just script fdisk or it's
equivalent) and I wrote a small NT program to allow this from the NT
system.  I used the NT rcmd to both execute the change active command
and also the normal NT shutdown (with reboot) command.

It's useful to change the active partition back to NT once the Linux
system comes up -- that way just pressing reset on the machine will get
NT back (but watch out for file system damage on the Linux system).

An alternative idea would be to set the machines to boot from the network
and figure out a way to have this either boot Linux over the network or
boot the local Windows system (should possible but I don't know how).
Then you could change which system got booted from the DHCP server...