Robert Pogson

One man, closing all the windows.

Posts Tagged / terminal server

  • May 10 / 2009
  • 2
Linux in Education, technology


Resistance to change is a defensive measure we all have to prevent wasting time learning something new for the sake of change. It can go too far. It has gone too far the way many retain that other OS. You know the kind:

  • never used anything else
  • hires someone every year to re-install/delouse that other OS or pesters an acquaintance to do it for less
  • accepts the idea that computers slow down (HAHAHA!)

These behaviours are irrational acts of the lazy. They are not idiots incapable of deeper thought. They are just using poor judgment and are resistant to change. The Blog of Helios does use the “idiot” term today. I guess enough resistance to change warrants the term but I think “stupid” is more appropriate. There cannot be that many idiots in the gene pool or we would not have gotten this far as a species.

I try not to be stupid but I did use that other OS for far too long:

  • I used a dozen different architectures of hardware, some even without an operating system, just stand-alone programmes
  • I like the old days of automobiles when anyone with wrenches and screwdrivers could fix their own vehicle. I try to fix my own PC and I rarely am stopped
  • my computers do not slow down. I run GNU/Linux. It has no brakes.

I had an example of this last item in operation in my school this week. I converted a lab to use GNU/Linux by adding a 5 year old PC as a terminal server and converted the 20 PCs in the lab to thin clients. It was a struggle because of various hardware and software issues like having to edit the boot loader configuration of that other OS to preserve it (Why? Some resist change…), many hardware problems in the old equipment (Remember 4MB video cards?), but it was worth it:

  • booting of clients in 30s instead or 3 minutes
  • login takes 5s instead of a minute or so
  • the largest application opens its window in 2s

This weekend, I added four more clients. The users of that other OS, who find they have to have the latest processor just to keep the bloatware moving fast enough cannot understand how one old PC can give 24 people good performance simultaneiously but it is easy if you

  • waste no cycles doing M$’s bidding
  • do not waste cycles running malware
  • do not clog network connections with spam
  • avoid features like “roaming profiles” which suck the life out of your network

So, including a switch from that other OS, my old PCs actually speed up! Isn’t that a refreshing change? I converted ten year old clients and a five year old PC into something wonderful. Students are excited about it and the increased performance is an obvious reward for the effort of changing. Most people are not stupid. They just need a little guidance. By asking the old boxes to do less, they get it done sooner. Simple concept. It works.

I believe if you cannot describe in numbers knowledge is of an uncertain kind:

  • the clients use 48 MB of RAM to do the job now instead of 384 MB and swapping madly with XP
  • the clients use only about 20% of their CPU time when busy
  • the clients need only about 2 megabits/s of network bandwidth each so there is no bottleneck at the gigabits/switch/ NIC on the server
  • the server PC has 2 gB RAM and runs at about 50% CPU utilization on AMD64 1.8 gHz

Those used to their machines dragging with fragmented file systems and the like would appreciate a machine giving snappy performance with 2000 context switches per second. There is no bottleneck in this system except RAM is a little tight (swap reached 1.6 gB), but then I am running a LAMP stack on the same machine… Those who object that the students are not all working on 200 MB images with GIMP are being picky. Students read, write and think. This system works for them.

Want to take a tour of the lab? What have I left running?

sh-3.1$ ssh old
Last login: Fri May 8 21:20:34 2009 from
pogson@old:~$ su
old:/home/pogson# nmap -sP 192.168.0.*

Starting Nmap 4.62 ( ) at 2009-05-10 09:12 CDT
Host old-o07 ( appears to be up.
MAC Address: 00:0D:88:36:C0:F3 (D-Link)
Host old-o08 ( appears to be up.
MAC Address: 00:0D:88:36:C3:19 (D-Link)
Host old-o12 ( appears to be up.
MAC Address: 00:15:E9:B0:FD:12 (D-Link)
Host old-o15 ( appears to be up.
MAC Address: 00:50:BA:AA:54:79 (D-link)
Host old-o16 ( appears to be up.
MAC Address: 00:50:BA:86:5E:B5 (D-link)
Host old ( appears to be up.
Nmap done: 256 IP addresses (6 hosts up) scanned in 1.697 seconds
old:/home/pogson# for f in 7 8 12 15 16;do echo $f;ssh 192.168.0.$f cat /proc/cpuinfo|grep z;done
cpu MHz : 451.035
cache size : 64 KB
clflush size : 32
cpu MHz : 863.875
cache size : 256 KB
clflush size : 32
cpu MHz : 451.034
cache size : 64 KB
clflush size : 32
cpu MHz : 451.040
cache size : 64 KB
clflush size : 32
cpu MHz : 601.396
cache size : 256 KB
clflush size : 32

There. The typical CPU is 450 MHz and the caches are 64kB. They make great thin clients and lousy clients for that other OS. Should we chuck them and pollute the planet? Should we burn less fuel by switching to modern hardware? Yes, if we use thin clients and a hot new server, the performance will be a bit better and we will use a lot less power, but this is what we have with which to work. We do the best we can and the students appreciate it.