VB: [SPAM] Re: multiple thin client servers

[Knut Yrvin]

Thursday 23 November 2006 16:18, skrev Mattias Hemmingsson:
> But skolelinux don?t have any solution to cluster edu servers.
> And ltsp-mosix is too old to use.

What do you mean by "don't have any solution to cluster edu servers"?

Do edubuntu have Linux Virtual Server as default, and a path to administer the 
system who a teacher with less computer skills are able to administer?

Linux Virtual Server is installable from Debian archive, and thereby 
accessible for Skolelinux users too. 

Skolelinux is extremely focused on easy of use when it comes to enterprise 
municipality wide installations. Our experience is that "server clustering" 
is more easy to do on service level. Letting services with heavy load run on 
different machines. We are also investigating clustering LTSP-servers (for 
thin clients) doing load balancing with LTSP out of the box. 

Clustering is doable, but not recommendable for teachers or computer operators 
with less or no prior knowledge of clustering (we are talking about 
municipality computer staff here, not a top notch Debian developer). 

Half thick clients (diskless) are also an important strategy. Today it's 
difficult to get reused machines with less than 800 MHz processor. Then it's 
possible to connect 150 half thick clients to the schools server. Diskless 
PC's is better in handling movies, heavy flash animations etc. 

So my question. What operational and technical argument says that clustering 
on server level give any vallue for a municipality with 800-2000 PC's?

I think you are recommending a solution that could be tough to administer for 
an average municipality computer staff, running GNU/Linux on 10-20 schools. 
The Ministry of Education and Science in Norway paid 100,000 Euro to collect 
experiences with large deployments of GNU/Linux systems. English version:  

http://developer.skolelinux.no/artikler/2006-04-02-debconf6.pdf

The other issue is use of memory. Real life use shows that Xfce and GNOME 
desktop uses more memory than KDE as a window manager (with end user 
programs): 

http://ktown.kde.org/~seli/memory/

After my knowledge this practical fact, makes it possible to connect 50-70 
thin clients to a 4 GB server with the KDE based Skolelinux. After what I've 
read there are recommended to install 30 thin clients with Edubuntu. Xfce 
does start fast, but it uses more memory than both Gnome and KDE in real 
life. KDE uses less memory than GNOME. 

For a school that wanna reuse a lot of thin client machines from 1995 until 
2001 (160 MHz - 500 MHz  CPU), they need to use almost twice as much servers. 
Our calculation, shows that this could double the amount of servers - just by 
choosing a more memory intensive software. 

> To cluster server I'm looking at LVS to load balance the servers.
> And then Webmin to cluster the server so package and shell scripts are the
> same on all servers.

After what I've heard Webin is not maintained in Debian main. Oliver wrote 
that he expect no admin tool to run in a web-server on Edubuntu. The tools 
need to both run as a KDE and GNOME application. 

So to sum it up Mattias:
- You are recommending tools that is not maintained. Is that wise on 
  solutions with 5-10 years life span?
- You are recommending technical complex solution that could be to hard 
  to implement for an average computer operator at municipality level. 
  Does this help when convincing municipalities to switch from 
  Windows to GNU/Linux?

My worries: The complexity and non maintained packages will stop or hinder 
deployment of Edubuntu and Skolelinux, because the municipality staff then 
believes Windows server is more easy to use. Then they roll out Citrix that 
gives 3-4 times higher operational cost than thin clients on GNU/Linux. 

Best regards

Knut Yrvin