[Beowulf] pxe boot an arbitrary distro from a CD drive on the headnode?

[David Mathog]

Is it possible to have a compute node PXE boot a distro
mounted in the CD on the headnode?

I've been using systemimager to clone nodes, and generally that's
been fine - until the other day when an install went awry on one
node and I needed to get some data off of a partition on that
node before repartitioning.  The node was no longer bootable from
the hard drive or the network (lilo problem, the partitions
it expected were all off by one block).  Systemimager's "boel"
didn't have the tools I needed (minimally, a way to login
remotely and rsh) and there was no CD drive on the node.
Both a Knoppix CD and a PLD RescueCD were handy, either one of which
would have done the job, but the CD drive was in the head node.
In the end I pulled the node, a CD drive was scavenged and
installed, Knoppix was booted and the data copied off.

Not very elegant.

I've been through a bunch of the HOW TO's and they describe how
to:

1. set up a diskless client - which isn't what I want here since
the distro to be run is on a CD.
2. run a floopy image or program like memtest86.  Also not the goal
here.

Surely somebody must have written some sort of shim program
that can be booted via PXE to make the remote CD drive (NFS
exported/mounted) appear local enough on the compute node to
serve as a bootable device?

The PLD Rescue CD claims to be PXE bootable already, but nowhere
have I found instructions for doing so.

Thanks,

David Mathog
mathog at caltech.edu
Manager, Sequence Analysis Facility, Biology Division, Caltech