My Classroom needs help
 

We have an Edubuntu server with 25 diskless stattions setup in a classroom for K-8 students. The server is a dual processor system with 1.5GB of data. Classroom is as follows:
We've got a school that is in dire need of help diagnosing a issue where all students are getting HORRIBLE response time during class hours.

Specs are:
o Dual 2.2 GHz Xeons
o 1.5GB memory
o SCSI and IDE drives
o Dual LAN cards

o Server provides DHCP and BOOtP to the LAN machines.
o all 25 LAN machines are in the same subnet
o LAN machines are using CD to boot a startup that allows them to find the server for loading.
o ALL student operations are on the server after login.
o Lan is 100Mb ethernet

The server is running about 75% utilized when the kids are on it.

The LAN users PCs power on and boot to a logon screen. When students enter their userID and password, the get a GNOME desktop from the server. This desktop runs for every student in the classroom. Even though when the server is booted, the individual PC that are booted on the LAN after the server is reasonbly fast.(25 PCs to login screen in about 2 minutes). But
when the students logon, it can talk up to 10 minutes to get a desktop. Further, their application that they try to use is so slow that class could be over before they get Open Office Open to each desktop(this is an example application).

The teaching experience is negatively impacted.

I'm suspecting that this is because the server cannot get the work out to the stations

Can anyone suggest what we should be looking for?
Has anyone else had this similar issue?

Can anyone help?

A few ideas for things to check.

Is this a new problem or have you always had this problem? Did this problem appear slowly as you added clients to the network?

Does the server have enough RAM?

Do the clients have enough RAM?

Does the server have enough swap space?

Do the clients have a local disk with a swap partition?

Are the server disks slow? New disks are screaming fast and they are really inexpensive.

Use wire shark to see if your network has a lot of errors such as duplicate packets and out of order packets. That might indicate a hardware problem somewhere.

http://wireshark.org/

Make sure that the network cards are using full duplex operation for maximum speed.

Check the log files on the server for any kind of repeating problem. Security problems can cause a lot of overhead. Hardware problems may or may not be listed or may be difficult to identify from the log files. Nevertheless they are always a good place to check for any problem diagnosis.

Try turning off one client at a time leaving the others running. Does the performance on the clients improve when one client is off? That machine may have a problem that is slowing down the network. Check the network configuration and the network card on that machine.

I'll add to this post if I think of anything else. :)

I agree with the previous post. To add to it, you need to narrow down where the problem is coming from. Also make sure you are using a good switch and not a hub. Try using less workstations to see if the problem is reduced or turn on 5 workstations at a time until you are able to pinpoint where the problem is coming from.

Do you have a NFS server to export some necessary directories to diskless workstations?

Has the administrator create directories for each diskless workstation, containing startup files and programs?

All space for your workstations is on a single disk on server or is breaked into 2 or more (SCSI) disks?

How look dhcpd.conf file (just an example for one workstation)?

How about TCP window size (wsize)?

The xorg.conf file loads or not glx module? (better not)

I will begin pinpointing this tomorrow
 

Thanks for the suggestion to get us started. I will post the finding, soon.

One question that I have: I cannot find ANY documentation that indicates whether the LTSP compresses its traffic to the terminal? (I am aware that X2 (and others) compresses the display/session traffic between the terminal and the server for each user's desktop. But, LTSP ????)