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2. Basic principle

As already said with this setup the clients share basicly the entire root-fs with the server. But the clients ofcourse only get read access to it. This is basicly how things work.

2.1 Things can't be that simple

Unfortunatly things aren't that simple, there are a couple of problems the overcome with this simple setup.

Each ws needs its own writable copy of a number of dirs

A normal linux setup needs to have write access to the following dirs:

  1. /dev
  2. /var
  3. /tmp

There are 3 solutions for this, of which one will only work for /dev:

  1. mount a ramdisk and populate it by untarring a tarball, or by copying a template dir.
  2. create a dir for each ws on the server and mount it rw over nfs.
  3. With kernel 2.2 devfs can be used for /dev, this is a virtual filesystem ala /proc for /dev.

As you can see, there are a number of ways to solve this problem. For the rest of this Howto the following choices are assumed:

Write access to /home might be needed

Not really a problem in every unix client/server setup /home is mounted rw from the server so we'll just do that ;)

How does a ws find out it's ip so that it can communicate with the server?

Luckily for us, this problem has already been solved and the linux kernel has support for 2 ways of autoconfiguration of the ip-address:

  1. RARP
  2. Bootp

Rarp is the easiest to setup, bootp is the most flexible. Since most bootroms only support bootp that's what we'll use.

What about ws sepecific configuration

On redhat most system dependent config files are already in /etc/sysconfig We'll just move those which aren't there and add symlinks. Then we mount a seperate /etc/sysconfig on a per ws basis. This is really the only distribution dependent part on other distributions you can just create a sysconfig dir, move all config files which can't be shared there and create symlinks. Also /etc/rc.d/rc3.d, or symilar on other dists, might need to be different for the server resp the workstations. Assuming that all ws run the same services in runlevel 3, we'll just create a seperate 3th runlevel for the workstations and the server:

  1. Create both a /etc/rc.d/ and a /etc/rc.d/rc3.server
  2. make /etc/rc.d/rc3.d a symlink to /etc/sysconfig/rc3.d
  3. make /etc/sysconfig/rc3.d a symlink to the apropiate /etc/rc.d/
  4. replace S99local in by a link to /etc/sysconfig/rc.local so that each ws can have it's own rc.local

Miscelancious problems

There are a few problems left:

  1. /etc/rc.d/rc.sysinit needs /var, so /var needs to be mounted or created before /etc/rc.d/rc.sysinit is run. It would also be nice if the ws-specific /etc/sysconfig is mounted before any initscripts are run.
  2. /etc/mtab needs to be writable:

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