multiple install servers; memdisk

[Steffen Grunewald]

Hi again,

no problem this time, but an idea:

to distribute the load during installation of a bigger (>10 machines) 
cluster, it would be nice to have multiple installation servers, the
configuration and mirror trees of which are in some way kept in sync.

This would require
- having DHCP servers running on them
- somehow telling FAI to use one of the servers (patch the nfsroot
	line to reflect the actual server, can be done by the mirroring
	script)
  and
- having a multi-headed fai-chboot 
  or
- sharing /boot/fai/pxelinux.cfg/ among all servers.
- The servers should also share ~fai (but this is not absolutely
	necessary - it only makes things easier).

The BOOTP/PXE/DHCP requests would be answered by the server with the
shortest response time (probably the lowest load), and installation
would use one of the identical nfsroot's (except sources.list, perhaps)
and fai config trees.
When the installation is done - and that's the crucial point IMHO -
the pxelinux.cfg/* file must be renamed on all servers - otherwise a 
reboot could connect to another server and restart installation over
and over, and there might lurk some installation on reboot somewhere
even if by accident the same server is connected for DHCP query.

Anyone out there running such a setup, and willing to share?
It would even be possible to use different servers for nfsroot and
logging, etc etc pp.


While I am here: I'm looking into memdisk to do automated BIOS updates.
Is there a simple way to tell the server(s) to remove the PXE link
when done? (I could imagine to try to TFTP a file that isn't there,
and watch the messages for this particular error, then translate the
IP to hex notation and pick the file below pxelinux.cfg - a hack but
one that has been working with our RedHat cluster for ages)


Cheers, and thanks for your patience,

 Steffen

-- 
Steffen Grunewald * MPI fuer Gravitationsphysik (Albert-Einstein-Institut)
SciencePark Golm, Am Mühlenberg 1, D-14476 Potsdam * http://www.aei.mpg.de
* e-mail: steffen.grunewald(*)aei.mpg.de * +49-331-567-{fon:7233,fax:7298}
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