[K12OSN] LTSP CentOS5 slow

"Terrell Prudé Jr." microman at cmosnetworks.com
Tue Dec 2 17:49:28 UTC 2008

jones yeates wrote:
> > >From the readings that top is showing the server is under almost no
> > load .16 ( if this was when there were some TC's connected to it). Why
> > don't you post what the make/model number of your switch is.
> >From what I can remember the switch is a BayStack, I don't know what 
> the model number is.  It has 24 ports that are 10/100's and a 
> Cu Gigabit uplink. 
> > >From the error that Jperf is throwing you do not have Java installed on
> > your server. This is just about a must. So,, do an ' yum install java '
> > then your Jperf will run without a hitch on your server.
> yum install java doesn't work.  You have to go to the site and 
> download the rpm.....
> I haven't done it yet, but I plan to.
> Yesterday I had my server "heavy" day.  Things worked at normal 
> speeds.  I am not sure what happened last week.  However the server 
> was extremely slow.  I used the System Monitor and watched it all day. 
> Yesterday, when things were slow it was either:  a lot of network 
> usage or CPU usage, but not both.
> In the morning the students were on Window boxes using Flash and 
> Samba.  I think some of them were working directly off of the server:  
> saving/executing.  I think that might have slowed things down.  I 
> asked them to copy the file onto their desktops and work from there 
> and then save it to their folders.  It seemed to work a bit better.

Ah, now that will affect things in a big way.  If you've already got a 
lot of disk I/O going, that will certainly slow things down.  In your 
situation, I'd have a physically separate, dedicated file server with 
hardware SATA RAID (level 5 or 10) and at least six spindles (hard disk 
drives); the more spindles here, the better.  Any time I do any heavy 
disk I/O on my K12LTSP server here at home, it slows down the server.  
Of course, my server has only a SATA RAID 1.

About five years ago, I had installed a K12LTSP server into a 25-station 
lab, using Pentium II's as EtherBooting thin clients.  It was a dual AMD 
Athlon MP, used twin 80GB EIDE disk drives, and had 4GB DRAM.  It was 
also one of the school's major file servers.  The server was not 
slow...but only because the DRAM caching was saving my butt (the K12LTSP 
2.12 of that day used way less DRAM).  Today, I would never try that.

> During the afternoon (they were on a Linux box), there was no 
> noticable lag.  I also asked the students to try to use Opera instead 
> of Firefox.  They complained a bit but it was nice to see the CPU 
> numbers go down.

Have them try Konqueror as well.  It takes wonderful advantage of shared 
libraries (thus lower DRAM usage) and also will find/use the Firefox 
plugins (Flash, etc.).  Further, it comes with stock K12LTSP and thus 
works with "yum update".

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