[K12OSN] Slow speed

"Terrell Prudé, Jr." microman at cmosnetworks.com
Sat Jan 22 17:40:00 UTC 2005

Bjørn Roger Rasmussen wrote:

> Hello people!
> I run a K12LTSP 4.2.0 setup at one of the schools I have the computer 
> responsibility for. The server is an old PC with the following 
> configuration:
> - Intel P 4 1.6 GHz, 1 GB RAM, 80 GB IDE harddisk WD with 8 MB cache. 
> 100 Mbit/s network.
> 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.
> Before I began to run K12LTSP I used Skolelinux 
> (http://www.skolelinux.no/). The users at the 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.
> 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.
> Where would you think is the biggest bottleneck in my setup? Should I 
> have had a better server? Which parts of the server has the most 
> importance for the speed at the thin clients?
> Bjorn Roger Rasmussen
> EDP employee - local government of Eigersund, Norway.

Hello Bjørn,

Jeff Kinz's recommendation about the CPU and the DRAM is correct. I'd go 
with nothing less than 2GB DRAM for 15 thin clients, and in actual 
practice I always use 4GB.

Additionally, you should have Gigabit Ethernet on your server, hooked up 
to a Gigabit port on your switch. There are those who say no, you don't 
have to do that, but in my experience, 100BaseTX on the server works 
only for maybe 5 graphical thin clients at a reasonable speed. Note that 
I said "switch" and not "hub/repeater." If you're using hubs, get rid of 
them and replace them with switches, very much preferably one with a 
Gig-E port. I also agree with Jeff about 100BaseTX on all thin clients. 
Though 10BaseT will work, it's a bottleneck.

Your thin clients are much more than powerful enough. An 80386-33 with 
the PCI bus and 32MB DRAM would do the job nicely, and I use old 
Pentium-166's and Pentium-233's with 32MB DRAM in my deployments. They 
are wonderful thin clients. I've also used old Apple PowerMac 5200's 
(75MHz CPUs) with 32MB DRAM; the only major downsides to the 5200's are 
that they support only 640x480 with 256 colors (PowerMac 5400's and up 
are better about that) and only 10BaseT Ethernet. Even so, they're still 
quite useable.

With regard to your disk drive, I also use 80GB IDE disk drives in my 
K12LTSP server (software RAID 1 through the Linux kernel). Twenty-five 
stations are on it, plus it's a file server for the entire school to 
use. In all cases to date, response time has been fine on my server, but 
then, my server has twin Athlon 1.47GHz CPUs and 4GB DRAM in it. You 
actually can get away with a standard IDE disk drive if you have 
sufficient DRAM, so you might not have to upgrade your disk. It depends 
on what you have your kids--and in my case, the staff as well--doing.


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