[K12OSN] multiple LTSP servers same network: tips/ tricks/ handouts

[Les Mikesell]

>From: "Dennis Daniels" <ddaniels at magic.fr>
> I want the main server.ltsp.one on dhcp response on 100-120.
> server.ltsp.two dhcp response on 121-130 but the authentication of
> having the /home dirs is causing me no end of anguish. Accessing the
> home directories via NFS failed flatout. NFS would not play nice on
> k12ltsp 4.1/FC2 even for a seasoned linux buddy of mine.

Can you elaborate on how NFS failed?   If you mount an existing
/home into /home on a new server, the only requirement should be
that the user/group id numbers are the same for each login on both
machines.  If you use LDAP or NIS, this will happen automatically
across machines.  If you don't, you have to make sure that the
contents of /etc/passwd, /etc/shadow, /etc/group, and /etc/gshadow
stay in sync between machines.

> Make no mistake, I love what I've got working now. But, the network is
> slow and my student's protests are growing louder for paper and pen.

Note that network load may increase if you use NFS and have all
the clients and servers on a flat network.   If the network is the problem
instead of your CPU speed you should use a different NIC  on the
servers for the NFS traffic.

 > I am a poor teacher, not a rich school district. Is there anything in
> the works (next version of LTSP?) that makes it __easier__ to add a
> second, even third server, to existing networks without increasing user
> authentication problems/home directory issues? I ask because I know that
>   Mandrake will ask you where the home dir will be located...and having
> read that Skolelinux has an authentication/multiple server configuration
> already built in(?).

Someone mentioned here that you can use one machine running
Skolelinux as the authentication and home directory server to take
advantage of the canned LDAP setup, configuring the k12ltsp's
to use it.   But, if your servers are identical you can just copy
the passwd/group files after any changes.

> Is there anything in the LTSP that will ask how many servers the admin
> wants to set up to support the LTSP network? I use webmin but there
> isn't thing nice in there that says, "Ah, your using LTSP... I see
> another LTSP server offering DHCP. Would you like to have the second
> server reference your existing home directories?"

One NFS mount in your /etc/fstab should be all it takes to make the
home directories appear where you want them.  Webmin does have
a cluster mangement option to add the same users across machines
if you don't use LDAP/NIS but I haven't used it.

> I need to squeeze more performance out of my single server(now) 35+ node
> network before parents/ stakeholders step in and say, "Enough, you
failed."

Are you using a gig connection between the server and switch?

> I'm not stupid but there are some critical pieces missing in the
> documentation and narratives on how to get more out of LTSP network on a
> real classroom size of 35 plus students without spending thousands of
> dollars on new servers and clients.

How many clients can you run before you see problems?  I think you
should have 4 gigs of RAM and a gig uplink, but otherwise your
server sounded OK.

---
    Les Mikesell
       les at futuresource.com