[K12OSN] Slow speed

Jeff Kinz jkinz at kinz.org
Sat Jan 22 15:37:25 UTC 2005

On Sat, Jan 22, 2005 at 10:22:05AM +0100, Bjørn Roger Rasmussen wrote:
> Now with K12LTSP as system the people at the school are complaining about 
> the speed. High response time when they shall start or use normally 
> programs etc.

> Before I began to run K12LTSP I used Skolelinux 
> school liked that solution, but it was a night mare for me to maintain the 
> network. I did not get any complaint about the speed when I run Skolelinux.

Does this mean that you used to run all your systems with local hard
drives?  If so, then your current slowness problems is a result of
either your network, or your server.

> - Intel P 4 1.6 GHz, 1 GB RAM, 80 GB IDE harddisk WD with 8 MB cache. 100 
> Mbit/s network.

I suspect that since you have a 100 Mbit network, assuming all the
thin clients are using 100 Mbit cards and not 10 Mbit cards, that your
problem is your server, not your network. Specifically you have three
potential weak points in your server.

	1. For 10-15 X clients, 1 GB of ram is very minimal. 
Depending on what applications are being run, you probably need more
than that. How to find out: when all your clients are being used (really
being used, not just logged in) run top and look at how much swap space
is being used. If you are using a lot of swap that is an indication that
you need more RAM. What window manager and applications are the clients
running? Based on my past experience, you need at least 100 Mb of RAM
for each client even when using a minimal window manager(icewm) and
doing only internet browsing or word processing. This means that your
server needs at least 1.5 GB of RAM and based in price points you would
be better off going right up to 2 GB. Buying RAM in large chunks costs
less money, and if your client machines are doing anything more than a
minimal amount of work you will need more than 100MB per machine.

You may have heard reports of people running 40-100 clients with only 
1 GB of RAM.  This works ONLY when the client machines are not running
X-Windows (being used only as telnet/terminal appliances).

1GB of RAM should be about (USD) $100 - $150

	2.  CPU 1.6 GHz isn't real fast.  Evaluate the output of top or
other load monitoring tools to see if you can benefit from a faster
CPU.  A 3 GHz P4 runs about (USD) $300.

	3.  Disk.  If you are hitting the disk for swap space definitely
upgrade your RAM first. Then, if the applications are still making heavy
use of the disk, you may want to upgrade to a disk with more cache
and/or a faster transfer rate.  SCSI and SATA are both generally better
than IDE, albeit more expen$ive.

	4. (4 of 3 :)  Network architecture - make sure all clients are
running at 100 Mbits and not 10 Mbits.  Make sure all switches or hubs
repeaters, and cards are running full duplex mode.  Make sure all the
cabling is clean with no reflections (reflections cause collisions and
retries).   Run ifconfig on each client and the server to see if any of
your machines are seeing collisions.

> The server shall serve about 10 – 15 thin client computers. The thin client 
> computers are old computers with specifications running from Pentium 166 
> MHz with 64 MB RAM and better.
Linux/Open Source:  Your infrastructure belongs to you, free, forever.
Idealism:  "Realism applied over a longer time period"
http://www.fedoratracker.org http://www.fedorafaq.org
Jeff Kinz, Emergent Research, Hudson, MA.

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