Re: [seul-edu] [Fwd: Computers in the classroom]

[Ray Olszewski <ray@comarre.com>]

At 09:38 AM 9/23/00 -0500, you wrote:
>I am having trouble in my new Linux lab with machines losing the 
>signal to the monitor.  We are rebooting the machine to get the 
>signal back, which takes 5-10 minutes.  In a 40 minute class this is 
>some bad down time for students.  I don't know if the problem is 
>Linux, our new computers, or our power supply is being stressed by 
>the new machines.

After reading Robert Hopcroft's response, I am mostly struck by how little I
understand about what the problem actually *is*. "Losing signal to the
monitor" sounds like a precise description, but it really is not. Could I
ask you to expand on the actual symptoms with some details --

        are the hosts running X or not? If yes, what Window Manager and
                if applicable, what desktop environment?

        when the signal is lost, have you tried switching to a different
                virtual terminal? To what effect?

        do you have a screen saver running? 

        when they fail, can you still log into the hosts via telnet or
                ssh? [If you can, rebooting that way will be faster than
                5-10 minutes, most likely -- it sounds like you are
                hitting the reset button, whihc forces an fsck of your 
                filesystems]

>Our machines:
>AMD Athlon (tm) Processor
>cpu MHz - 705

More interesting would be what video card you are using. You don't seem to
say. Assuming you are using X, what X server are you running?

>
>Using: Caldera2.4
>
>Memory on Server:
>Total - 124.9 MB
>Free - 4.9 MB
>Shared - 60 MB
>Buffer 26 MB
>SWAP - 252 MB
>Free SWAP - 249 MB
>
>Memory: workstations
>Total - 62 MB
>Free 5 MB
>Shared - 37 MB
>Buffer - 1 MB
>SWAP - 128 MB
>Free SWAP - 123 MB

Please provide this in the actual form of the output of "free". Summarized
this way, you leave out some helpful information (like the entire second
line or output). 

>We are currently changed from a 58K internet hook-up to 560K cable 
>modem hookup.
>
>  I have never heard of this type of processor before.  How does it 
>compare to something like Intel?  Would the machines cause the loss 
>of signal?

It is a pretty standard alternative.

>  We use Caldera2.4.  We have disabled the power management to 
>prevent the machines from shutting down to conserve power.  Could we 
>do something different to prevent the signal loss?

Disabling power management is a pretty standard practice for a setup like
yours. It should not cause problems. I don't understand yours well enough to
know if you should do something different here.

>  We have reached the peak amps that we can use on the circuit 
>breakers in our lab.  Could power fluctuations cause our loss of 
>signal to the monitors?

Not impossible, but not likely either. Are you actually porring the circuit
breakers? If not, how did you determine that you are at the peak?

>  Is this a common problem for Linux in general?  I am new to the 
>operating system.

If "this" is the video problem you are asking about, then no, it is not common.

>  We are currently running our 30 machines as stand alone 
>workstations with students logging in as a generic student and saving 
>to disks.  Should the computers we have be difficult to set up in a 
>server based network with students saving data to the server and 
>accessing it by logging it at any computer in the lab?

Most likely no, but once again the details are essential. Examples of
relevant details: What are the students actually doing (what apps? X or
console?)? How fast is the network? THe server might need more memory in
this usage model than what it has now.

[rest deleted]


--
------------------------------------"Never tell me the odds!"---
Ray Olszewski                                        -- Han Solo
Palo Alto, CA           	 	         ray@comarre.com        
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