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This page is suposed to become the instructions in how you can run Diskless workstations from a skolelinux3.0 installation. Diskless workstations are also marketed using the term "LowFat Clients" or "Halfthin Clients". This page is suposed to become the instructions in how you can run Diskless workstations from a skolelinux3.0 installation. Diskless workstations are also marketed using the term "!LowFat Clients" or "Halfthin Clients".

?TableOfContents(2)

What

This page is suposed to become the instructions in how you can run Diskless workstations from a skolelinux3.0 installation. Diskless workstations are also marketed using the term "LowFat Clients" or "Halfthin Clients".

A diskless workstation is similar to a thin client in that it bootes from the network with pxe. But instead of running applications on the server and displaying them on the thin client screen with X. A diskless workstations mounts it's root filesystem from its next-server, and runs all applications on the local hardware. You can think about it like a regular workstation with a very long harddrive cable.

Why

  • to better utilize the power of your client hardware
  • to get a full workstation experience, with all local devices working correctly
  • but still maintain central configuration and no maintainance of the individual client.
  • lower the demands of the central server, or run more clients of the same server.
  • on a 100 Mbit/s network it's possible to run 150 diskless workstations compared to 50-60 thin client
  • <fixme: add more advantages>

why not

  • older hardware will be very slow as a (diskless) workstation, you should have a P3 800-1000Mhz with 256-512MB ram, or there about. Try for yourself and see if your hardware is powerfull enough as a diskless workstation.
  • the workstations will require more horsepower, and will be more noisy then a thinclient. you will have CPU fan and PSU fan noise. I have yet to find a resonably priced 100% silent computer with enough power. So you loose the 40 computers in a room and no noise experience you can get from thin clients.
  • fans means moving parts, moving parts means higher risk of hardware failure. a thinclient is less likely to display the aging syndroms that regular pc's experience. Like the noise from a worn out fan. Expect slightly more hardware issues with diskless workstations then you do with thinclients with no moving parts.

How

  1. prerequisites
    • a regular skolelinux setup with tjener and preferably internet access
    • a fresh installed skolelinux terra/etch thin client server, that you want to run diskless workstations from (this server is promoted as "next-server" by tjener's dhcp)
    • combined server work fine (You must not edit pxelinux.cfg/default and in dhcpd.conf you must only enable your workstations).
    • local swap on each workstation is recomended
    • /!\ enough space on /opt? It need to be at least 3.5 GiB.

          lvextend --size +1G /dev/vg_system/opt 
          resize2fs /dev/vg_system/opt
  2. Edit /opt/ltsp/i386/etc/apt/sources.list.
    • Because the CDs and DVD is not signed, one need to use network APT sources.
    • Add the security repository.

deb http://ftp.skolelinux.org/debian/ etch main
deb http://ftp.skolelinux.org/skolelinux/ etch local
deb http://security.debian.org/ etch/updates main
  1. Then run the command /usr/sbin/ltsp-make-client This will adapt your chroot /opt/ltsp/i386 to diskless workstation, and install the packages needed for a workstation there. If it fails for some reason you can run it with sh -x /usr/sbin/ltsp-make-client to get a more verbose output. (run outside the chroot)

/usr/sbin/ltsp-make-client
  • /!\ if you run this with bash you will end up with a minor bug in /etc/dhcpd3/dhcpd.conf. The default dash shell in Skolelinux-3.0 works fine.

  1. add nfsroot=/opt/ltsp/i386 to the end of the append line in /var/lib/tftpboot/ltsp/i386/pxelinux.cfg/default

    • if you don't you'll get an error on the client about not being able to mount /var/lib
  2. edit your main dhcpd.conf file located on tjener.intern:/etc/dhcp3/dhcpd.conf, you'll need
    • a next-server line pointing to the server serving diskless workstation root. ie the ltsp-server where you ran ltsp-make-client
    • remember to restart the dhcp service
  3. Connect your diskless workstation to your workstation network 10.0.2.0/23
    • The same client can function as thinclient or diskless workstation, depending on where you connect it. 10.0.2.0/23 for workstations, 192.168.0.0/24 for thin clients.

This is setup in the file /opt/ltsp/i386/etc/init.d/ltsp_set_runlevel If you want your diskless workstation on the 192.168.0.0/24 network, you may change this here

  1. boot your client.
    • if all went well you should be looking at the kdm login screen
  2. login and use your system
    • /!\ keep in mind your diskless workstations need to be added to your ldap netgroups, just like any other workstation. Otherways it wont be able to mount your HOME dir, and you won't be able to login.

example dhcpd.conf snippet

host static04 {
   hardware ethernet 00:00:00:00:00:00;
   fixed-address static04;
   filename "/var/lib/tftpboot/ltsp/i386/pxelinux.0";
   option root-path  "/opt/ltsp/i386";
   next-server ltspserver00;
   # next-server tjener; # for a combi server 
}

example /var/lib/tftpboot/pxelinux.cfg/default

prompt 0
default ltsp
label ltsp
  kernel vmlinuz
  append initrd=initrd.img root=/dev/nfs ip=dhcp  nfsroot=/opt/ltsp/i386

(you can only add a boot option for booting a locally installed operating system)

Upgrade Kernel

chroot /opt/ltsp/i386 
aptitude update
aptitude install linux-image-2.6.18-4-486
exit

Then you must prepare the system to use the new kernel

/usr/sbin/ltsp-update-kernels

Further Reading

Confirmation

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