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Re: Cluster Administration

In article <m0zcmrE-0007ziC@ralf.informatik.uni-stuttgart.de>, Rainer Dorsch <rainer@ralf.informatik.uni-stuttgart.de> writes:
> We have here a cluster of 30 SUN UltraSparcs and I am looking
> forward to see Debian UltraLinux. A major concern I have about Linux
> on UltraSparc is, that it seems to be difficult to keep on all the
> workstations exactly the same configuration and sharing diskspace
> using NFS.

> Currently, Debian package management is sufficient for a single
> workstation, but insufficient for a cluster. This problem has to be
> addresses sooner or later, if you want to run Debian on a
> workstation cluster.

> Maybe the Debian UltraLinux developers could try to find a solution
> for this problem, in the time they are waiting for Sparc64 support
> for egcs (this is a multiplatform problem and can be addressed on
> intel machines).

Utterly agree.

Here's some brainstorming.  Instead of waiting for the grand-unified
automated maintainer script solution (which would take about a year to
complete, assuming we can agree on the design), why not do the

Define two types of machines: 

* OS server; it is a special server that just serves up via NFS the
  disk for the clients

* clients: either diskless, or dataless (that would take some work; I
  don't think linux has a cache only filesystem yet, shame -- well you
  could have a local /tmp)

On the OS server, you have your actual Debian installation, and then
you have the "exported installation".  This is dpkg, which has
operated on a chrooted environment.  Complete with kernel, var, all
that.  Let's call the exported installation "export"

clients mount "export" via dhcp/bootp/tftp or what have you

clients have a locked down /var/lib/dpkg in such a way that dpkg
refuses to install/remove/configure anything when run from the clients

Once we've gotten this far we've solved the baseline requirement, but
it might be too restrictive that /etc is the same for all these boxes;
work out a way to overlay on /etc a la the nfsroot package....

All maintenance of the export system is done via dpkg on the OS server

The other problem here is that you have no way of reconfiguring the
clients during upgrade -- hmm!  That would be a little tricky.  At
worst, you take down all the clients for system maintenance.  At best,
you could work out a way to shove maintainer scripts execution out to
the clients...

What do you think?  I've never tried to run dpkg in a chroot
environment, but I don't see why it wouldn't work.  And with minimal
hacks required to dpkg.

.....Adam Di Carlo....adam@onShore.com.....<URL:http://www.onShore.com/>

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