Description (20 nodes):
     AMD K6-2 @ 400MHz 
     128 MB RAM 
     18 GB IBM hard drive 
     100Mb/s Ethernet 

     % cat /proc/cpuinfo
     vendor_id	: AuthenticAMD
     model name	: AMD-K6(tm) 3D processor
     cpu MHz	: 400.926356
     fpu	: yes
     bogomips	: 799.54

Makefile (example)
mpihello.c Compiling: Running: Others:
Use this script for testing the list of available machines at a given moment if your application is not starting (save it as checkm and run: "chmod 755 checkm; checkm mchf"). All are running 24/7, but ...
#!/bin/bash

a=`cat $1`

for i in $a; do
  if `ping $i -c 1 -i 1 >/dev/null 2>&1`; then
    if `ssh $i /bin/true >/dev/null 2>&1`; then
      echo $i
    fi
  fi
done