Linux X-terminal Overview
by
Alan W. Irwin

Last Updated: 2002 May 21

Top Details



hare = fast machine, tortoise = slow machine





xdm, kdm, gdm 
   100 BaseT network
X -query hare
X clients:
KDE, GNOME,
OpenOffice, etc.		 100 BaseT network X server controlling
monitor, keyboard,
and mouse



hare = fast machine, tortoise = slow machine





X-terminal Options

  1. Root file system mounted on tortoise disk.
    • Advantages: simplicity (no NFS). Most secure setup.
    • Disadvantage: must have hard-disk drive on tortoise.
  2. Separate root file system NFS-mounted on hare disk for each X-terminal (tortoise, turtle, slug, snail, etc.) The kernel is stored on floppy diskette file system with kernel parameters for networking and location of root file system configured with lilo.
    NFS v.3 kernel server 
       100 BaseT network
    		NFS kernel client
    • Advantage: No hard-disk drive required on any of the X-terminals.
    • Caveat: Each X-terminal must have a floppy drive.
    • Disadvantages: Must use NFS (which is inherently insecure until at least version 4 becomes available for Linux). Separate root file systems are fine for a few X-terminals, but do not scale well to the situation where you have hundreds of X-terminals.
  3. Mostly shared root file system NFS-mounted on hare disk for each X-terminal. The kernel is stored on hare and loaded into each X-terminal's RAM using and Etherboot boot ROM when boot is required. The Linux terminal server project (LTSP) is an example of such a system.
    DHCP server 
       100 BaseT network
    		DHCP Etherboot client
    TFTP server 
       100 BaseT network
    		TFTP Etherboot client
    DHCP server 
       100 BaseT network
    		DHCP kernel client
    NFS v.3 kernel server 
       100 BaseT network
    		NFS kernel client
    • Advantages: Scales well. Most of root file systems can be shared (e.g. /usr) which greatly reduces the required software maintenance effort. X-terminal requires no floppy drive.
    • Disadvantages: The initial setup is complicated. (36 ! steps required to finish boot and initialization phase according to LTSP). Even more chance for insecurity with additional protocols (DHCP, TFTP) required to retrieve and boot the kernel before the eventual NFS mount of the root file system.