[K12OSN] LTSP CentOS5 slow

jones yeates jones_yeates at hotmail.com
Sat Nov 29 00:54:05 UTC 2008

> Subject: Re: [K12OSN] LTSP CentOS5 slow
> From: brcisna at eazylivin.net
> To: k12osn at redhat.com
> Date: Fri, 28 Nov 2008 08:23:00 -0600
> Hi Jones,
> Please supply some specs of your server and how many TC's you are
> connecting to it.Is this a default install of K12LTSP5, or CentOS5 with
> ltsp on top of it? Have you updated the server since a default install?
> The FF update shouldn't have hindered the performance any just,, FYI.
> A few things to try. 
> 1. run top from a terminal while the server seems " slow ", and see if
> your memory is all used up,or if cpu is 100%.
> 2. You could download jperf,and install on your K12LTSP server as well
> as a (linux)laptop you have available. Plug your laptop into the switch
> that the TC's are plugged into. Run jpef in server mode on the server &
> run jperf on your laptop in client mode. You will see what bandwidth is
> available along with jitter and all that sorta geeky stuff.This piece
> has really helped me in finding were bandwidth is being used realtime.
> 3. Is the switch the TC's are plugged into a 'plug and play' switch? In
> other words a non-managed switched?
> 4. That is odd Firefox is throwing that error you posted. Did you
> install FF via yum? Is this error happening every time FF is launched,
> or hit and miss?
> You can download the jperf rpm at the URL below. You will need to
> install iperf, first, which is at the url as well.
>  ftp://eazylivin.net/server/jperf/
> Let us know your findings.
> Take Care,
> Barry Cisna
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I wasn't able to find the loopback and I'm curious if the switch has green lights because of the possible Wake-On-LAN abilities of the NIC cards.  The NIC lights are green when the computer is plugged in but turned off.

Currently all 30 TC's are off and its just 1 TC and 1 server.

To answer your previous questions:
There are max 31 thin clients.

Default k12ltsp5EL

2 15K rpm scsi drives in  software raid 1

6GB ram (serving max 30 students at a time)

1.  TOP output:
top - 16:40:27 up 4 days,  2:10,  7 users,  load average: 0.16, 0.24, 0.20
Tasks: 211 total,   1 running, 208 sleeping,   0 stopped,   2 zombie
Cpu(s):  2.9%us,  0.2%sy,  0.0%ni, 96.6%id,  0.2%wa,  0.0%hi,  0.1%si,  0.0%st
Mem:   3631812k total,  2337164k used,  1294648k free,   357848k buffers
Swap:  1036088k total,      160k used,  1035928k free,  1278744k cached

[I was tired earlier and Swapped Mem and Swap]  Memory looks like its being used up.  This is with just 1 TC running.

I have both window and Linux in my lab, after reading I noticed that I
could install iperf.exe on a Windows client and I won't need a laptop. 
I had key issues installing iperf on Linux, but it says it installed
it.  I installed jperf no problem, but when I tried to run it I got

Error occurred during initialization of VM

Could not reserve enough space for object heap

Could not create the Java virtual machine.

3.I believe that the switch is non-managed.  We just connected the cables in and away we went.

4.  Yes, I installed Firefox with yum.  I also updated a couple of times.  I updated it again today.  Firefox crashes every once in a while.  It was crashing more regularly before the update.

It seems to be fine when I turn the switch off/on.  If its just a couple of users then it seems to be running ok.  Once a class gets in its slow again.

I'm stuck again.


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