Which hardware?

Dan Young dyoung at mesd.k12.or.us
Fri Jun 16 04:30:48 BST 2006

Knut Yrvin wrote:
> Torsdag 15 juni 2006 19:38, skrev Dan Young:
>>> 15 * 128 MB = 1920 MB
>>> 1 * 256 MB = 256 MB
>>> Sum = 2,1 GB RAM ~ 2 GB RAM (on a server with 15 thin clients)
>> Uh, so 4GB for the 30+ Simon asked about? 4GB is the minimum for
>> this, IMHO.
> Yes. My mistake about the 15 clients! Yes, 4 GB is right for 30
> client. But it's not a minimum. Why? The key factor is concurrent
> users. Statistically there is seldom more than 60% of the clients in
> use. When installing 50 thin clients no more than 30-35 of them is
> concurrently in use at the most. So 4 GB is sufficient for 50 clients. 

I guess it depends on how you count clients. The term is ambiguous in 
terms of actual concurrent use. My experience is from classrooms where 
all seats are filled constantly and come in waves. 32 kids walk in the 
door, sit down, and log in within a very short period of time. This puts 
tremendous strain on a server.

Think about a teacher saying "...and now open OpenOffice Writer" to a 
big class.

>> One more recommendation; think about installing and using prelink to
>> speed up application launching. It's supposedly most effective on
>> large C++ applications (read: KDE, OpenOffice, Firefox). 30+ clients
>> all launching OO Writer at the same time can be interesting. ;-)
> The startup time for applications on a thin client server is really
> fast. It's faster than on a workstation. We have experienced that it
> takes 5-6 seconds to log in and start OpenOffice.org for 30
> pupils. 

I'd like some of those servers. ;-) I've seen more like 5-6 minutes for 
30 kids to do that on a dual 2.4GHz Xeon (somewhat memory starved at 2.5 
GB of RAM) stipulating the "all at once" scenario I described.

> Further, many of the advantages with prelink is merged in with gcc 3.X 
> and gcc 4.0.X. [edu|k]ubuntu Dapper uses GCC 4.0.3. With e.g Qt 4 and 
> new KDE 4.0 most of the dirty page swaping is fixed and optimised. But 
> that's 6-8 months ahead. 
>> Don't know how Ubunteros feel about prelink (it's in universe); it's
>> installed by default on Fedora.
> There are other areas that could be speeded up. In general and
> simplified there four ways to do this. But when using thin client the
> two first makes most effect:
> 1. To choose a more light weight approach, e.g change the windows
>    manager. Use iceWM or similar in stead of KDE or GNOME.  
> 2. To clean up and get rid of unnecessary libraries when starting up
>    KDE or GNOME e.g: http://www.osnews.com/story.php?news_id=13039
>    Developers work on the startup times in the GNOME and KDE projects.
>    This improvements is on it's way. 
> 3. Do smarter booting of the OS. Look at this presentation by
>    Margarita Manterola: 
>    http://www.marga.com.ar/~marga/debian/boottime/debconf-boot.pdf
>    (Ubuntu has done smart things already with Dapper ...)
> 4. To better utilise the new features in GCC, and clean up application
>    code that is slow or less efficient

All good things, especially the Xfce recommendation, I'm just trying to 
give practical advice about what to expect "right now". What might 
happen with Edgy (and Edgy+n) is probably better served on the -devel 
list. I'd rather set moderate expectations given limited information 
from a prospective user, letting their expectations be exceeded should 
circumstances provide.

Dan Young <dyoung at mesd.k12.or.us>
Multnomah ESD - Technology Services

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