[K12OSN] Multiple LTSP servers on a single subnet?

[Jim Kronebusch]

> > somehow control which server the clients connect to on a client by 
> > client basis (students to one server and staff to the other).  I'm 
> > assuming that there is some way to do this with MAC addresses?
> 
> I think you can do that if you configure the dhcp servers as 
> non-authoritative and do not permit both to answer unknown 
> MAC addresses but I've forgotten the details.  The other 
> simple-minded way would be to run the staff dhcp server on a 
> different port and require custom boot floppies to access that server.

The dhcp module in Webmin makes this fairly easy.  I haven't messed with
it much other than to block specific Mac addresses.  But it looks like
you can do all sorts of fun stuff in there.

But in thinking while I type, won't you have far more student machines
than staff?  If so this wouldn't your server loads be unevenly
distributed?  Would you be better sharing /home between them maybe even
in the manner of a previous post like /home/staff from server A mounted
on A and B and /home/students from B mounted on A and B?  The you could
evenly distribute the load across servers.

Thinking about the distribution, I have seen a lot of suggestions from
the simple first come first served method to complex scripting ideas,
but here is another.  I have seen before that DNS is capable of round
robin (here is my first google hit
http://www.zytrax.com/books/dns/ch9/rr.html#order ).  Couldn't an
internal DNS simply be setup with Round Robin enabled, and then the
configs from the LTSP servers setup by url instead of IP?  I understand
that this may not be possible with a conventional setup as in order to
get and IP you first have to hit a dhcp server and the initial dhcp
server will be the one to handle the rest of the requests.  But what if
tradition was broken and in a multiple ltsp server environment dhcp and
tftp were disabled on all servers except the master.  Then the master
was configured with the next server option called out with a url and not
a ip.  With this theory all servers would get an IP from the master
server along with a DNS entry that called out the internal server, and
the next server directive would call on the other servers in round robin
fashion.  Is this plausable?

Then you would still have the option to distribute NFS across multiple
servers with the /home/machinename method or by using the master LTSP
server as /home exported to the slaves.

Ah hell as long as I am typing anyway, what is the possibility of adding
a menu driven script on initial startup of ltsp to determine whether
this will be a Master or a Slave server, then depending on the answer
you would be given either the option to specify for Master what it is
the master for (LDAP/NFS/TFTP/DHCP/etc), if one of these options it is
not the master give an option for use server x instead.  Then if you
answered slave server get a menu allowing entry of either URL or IP of
the master server in your network for each service.  Then after going
through this screen the proper scripts would run for
mounting/exporting/authenticating/etc with the right information.  Also
allow this menu to be called on in the future to reassign/update
settings.  I am thinking similar to Authconfig under Fedora.

If any of this is possible it may help in getting to the next phase of
ltsp.  I am seeing more and more questions on 30+ client networks, and
it seems that in order to progress a system needs to be developed to
make it easy (for dummies like me) to cluster servers to handle more
clients.  

Okay I'm done :-)


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