16 Screen Wall

16 Screen Wall

Participants	Nooitaf, User:zmatt
Skills	Linux, X
Status	Active
Niche	Video artsy stuff
Purpose	Fun
Tool	No
Location	Space
Cost
Tool category

16 Screen Wall

16screen-thingy.jpg {{#if:No | [[Tool Owner::{{{ProjectParticipants}}} | }} {{#if:No | [[Tool Cost::{{{Cost}}} | }}

Since 9 screens are obviously not enough (see 9 Screen Wall 1), Petraea built a 16 screen one.

Power on and off

File:16 screen power button There is a power button on the bottom left that'll shutdown all machines when they're on, and power on all machines when they're off. The master node is key.

Power on

Button powers on master node, and this will do a wake-on-lan for the other machines.

Power off

Masternode powers off the other machines via ssh, and then will power down itself.

Machines

Default user on the master node is display. You can ssh as root into the master node on 16-wall-1.nurdspace.lan and ssh into the rest from there (192.168.255.x).

Machine 1

Master node
HP Compaq dc7600 Ultra-slim
Pentium 4 3GHz
2.25GB DDR2 533MHz RAM (2x 1 GB and 1x 256MB), max 3x1GB

Machine 2

HP Compaq dc7600 Ultra-slim
Pentium 4 3Ghz
1GB DDR2 533MHz (1x512MB and 2x256MB) Max 3x1GB

Machine 3

HP Compaq dc7700p Convertible Minitower
Core2 6300 @ 1.86GHz
1GB DDR2 533MHz (2x512MB) (max 4x2GB)

Machine 4

Asus 5S800-VM/Vintage
Celeron D 2.66GHz running @ 2.8GHz
2GB DDR (2x 1GB, no slots free)

Machine 5

HP Compaq dc7600 Ultra-slim
Pentium 4 3GHz
2GB DDR2 533MHz (2x 1GB) max 3x 1GB

Machine 6

HP Compaq dc7600 Ultra-slim
Pentium 4 3GHz
1GB DDR2 (2x512MB, one slot free, max 3GB)

Machine 7

HP d330 uT (DG285T)
Pentium 4 2.6GHz
2GB (4x512MB, no slots free)

Machine 8

Dell Optiplex GX270
Pentium 4 * 2.8GHz
2GB DDR RAM (4x512MB, no slots free)

Switch

HP 1910-24G JE006A

Current Status

Most of the scripting has been copied over from [9 Screen Wall 1] and is semi-working. In order to complete things properly, the internal networking needs finishing.

The screen setup script has been improved to:

#!/bin/bash
export DISPLAY=:0
export XAUTHORITY=~/.Xauthority
DISP1=VGA-1 #sometimes VGA-0
DISP2=DVI-I-1 #sometimes DVI-0
x=1280
y=1024

function setscreens() {
xrandr --newmode "$x"x"$y"_c 108.88 1280 1360 1496 1712 1024 1025 1028 1060 -Hsync +Vsync
xrandr --addmode "$DISP1" "$x"x"$y"_c #Could be VGA0 - check xrandr
xrandr --addmode "$DISP2" "$x"x"$y"_c #Could be DVI0 - chrck xrandr
xrandr --output "$DISP1" --mode "$x"x"$y"_c --rotate normal --output "$DISP2" --mode "$x"x"$y"_c --above "$DISP1" --rotate normal
}

function readscreens() {
raw=$(xrandr | sed 's/primary //' | grep 'connected' | cut -d ' ' -f 1,3|tr ' ' '.')
for q in $raw ; do
ID=$(echo $q | cut -d '-' -f 1)
DIMX=$(echo $q | cut -d '.' -f 2| cut -d 'x' -f 1)
DIMY=$(echo $q | cut -d '.' -f 2| cut -d '+' -f 1| cut -d 'x' -f 2)
POSX=$(echo $q | cut -d '+' -f 2)
POSY=$(echo $q | cut -d '+' -f 3)
if [ "$ID" == "VGA" ] ; then
  if [ "$POSY" == $y ] ; then
    VGA=1
  fi
fi
if [ "$ID" == "DVI" ] ; then
  if [ "$POSY" == 0 ] ; then
    DVI=1
  fi
fi
done
if [ "$VGA" == 1 ] ; then
  if [ "$DVI" == 1 ] ; then
    return 0
  fi
fi
return 1
}

setscreens
sleep 1
while ! readscreens ; do
setscreens
sleep 1
done

Quick discovery when I eventually rewrite this: XdmX will _not_ accept screens starting with numbers - they must start with a letter! So all remote screens have to resolve from the master correctly.

Internal IP range: VLAN1, 192.168.0/24, set untagged on #2-#8, tagged on #1
External VLAN: 2, set untagged on the external port and #1
The switch is set up on 192.168.0.254

The current idea is to set up DHCP on #1 on interface eth0.1, set MASQ up between the two interfaces, and allow DNS forwarding over that.