Introduction; Overview; Setup - HP xw3400 User Manual

Introduction

With the advent of multiple graphics cards in a system and with processors going to dual and multi
core, many technical users of workstations are looking for ways to support more than one user on a
single system. This is particularly useful as enterprise customers using workstations would like to setup
application servers in the datacenter with shared access by lots of users. Logging onto these shared
systems remotely via HP's RGS product (Remote Graphics Software) allows easy access to these
shared resources and supports as many users as the number of graphics cards in the system. The
other use of this technology is just to save money and space in a space constrained environment. By
putting 2 users on a single xw9300 or xw9400 workstation, for the price of a workstation and the
price of additional keyboard, mouse and monitor, you can support an extra user.

Overview

Adding multiple users on a single box with attached keyboards is made possible on Linux via
changes to the X11R6.9 changes (also on the X11R7 version). This version of X windows comes with
Red Hat Enterprise Linux 5 (RHEL5) and Fedora Core 5 (FC5) and Suse Linux Enterprise Desktop 10
(SLED10). This version of Xwindows can also be installed on other versions of Linux (such as RHEL4),
but this requires some work and HP/Red Hat does not support this. The key feature that is needed in
the new X server is a driver called "evdev" which enables input from all the USB devices on the
system without collision of the different Xservers that are running on a system. X 6.9 also prevents
graphics cards from stepping on each other and clearing each other's screens.
The xw9300 and xw9400 have dual PCI-Express x16 graphics slots, making it rather unique among
commodity workstations. This capability, coupled with the two dual-core Opteron processors,
provides an unprecedented amount of graphics processing power for a Linux workstation. The
notion of supporting multiple users with this box is very viable given this much horsepower.
This paper will walk you through some of the mechanics of how to setup such a system. It should be
noted that this process will take some patience, but should be pretty straight forward with the help of
this whitepaper.

Setup

The workstation hardware should be ordered as a unit and arrive with desired processors, graphics
cards, displays and memory. The extra keyboards and mice will have to be ordered separately. The
first step is to plug in the keyboards and mice as desired. Then reboot to get the kernel to recognize
the input devices so you can figure out the correct device files to use. Future changes to the USB ports
that are used for the different keyboards and mice will require changes to the xorg.conf configuration
file, so pick an initial configuration that you will not have to change much.
Next determine what the real input devices are by looking in /proc/bus/input/devices file to see all
the active hardware. Next to the Handlers line for each device, it should specify the filename for the
device files in /dev/input/ directory for the corresponding device (eventX for keyboards and mouseX
for mice)... however, I found that these can be wrong. The kernel driver seems to get a little confused
as you plug and unplug devices. To be sure you have the correct device file for each device, get
input from each device file and see what device actually responds.... Just wiggle each mouse and
type on each keyboard until the od command returns some data. Then break out of the command
and try it again for the next device file:
od < /dev/input/event0
od < /dev/input/event1
od < /dev/input/event2.....
(should give you data when you type on the PS2 keyboard)
(should give you input when you wiggle the PS2 mouse)
2