[K12OSN] CPU or Memory

["Terrell Prudé, Jr."]

Liam Marshall wrote:

>I posted earlier about trying to decide whether to upgrade the memory on
>the server, or the cpu
>
>I had a 3.06 GHz hyperthreading cpu and 2 GB of ram
>when 30 students would all try and load say, OOwriter, cpu use pegged
>and memory usage showed 1.9 out of 2 used.  It would be real slow, until
>all where in, then settled down slightly.  But web pages and something
>as silly as tux type would bog the whole system down.  I know something
>had to be done but could not choose.
>
>We settled on memory, upgrading to 4 GB.  Then I got nervous and ordered
>a dual cpu board and two Xeon 3.06 cpu's as well.
>
>Then I was frustrated yesterday when the server atx case I planned to
>use had the wrong power supply.  the ASUS PC-DL Deluxe motherboard I
>bought needed a SSI type 24 pin connector, mine was 20 pin.
>
>After some frustrating research I learned what the difference was
>between an SSI 24 pin connector and the power supply I had was, then I
>bit the bullet and went out and paid 185.00 plus tax for the right power
>supply.
>
>Then today I was frustrated again. After plugging in the power supply
>and connecting everything, I got nothing but a single loooong beep on
>power up. No video at all.  after two hours of frustration, I called a
>friend for a fresh perspective.  He brought over another duelly system. 
>We tried video card first, known working from his system.  Zip.  Then we
>tried his memory.  Voila!  My 4 GB Kingston memory was defective! 
>Sh&&%t!  All that wasted time.  
>
>Trouble was, my friend only had 2.5 GB of ram for me to try.  Everything
>is functioning great though, and I didn't have trouble with the new
>hardware.  Nics had to be configured, thats all
>
>So now, instead of changing two things, cpus and memory, I basically
>have a dual cpu machine, and 2.5 GB.  I plan to try out the system under
>load with the students on Monday, seeing as how I have no choice. 
>Replacement ram will take at least a week to arrive.  By the end of the
>day on Monday I will know whether doubling the cpu's solved the entire
>issue.  If it does, I will get my money back for the ram and leave it at
>that.  If it helps, but not enough, I will go for the ram to
>
>If anyone is interested I will post results Monday night.
>  
>

Yep, I'm interested.  As a certain U.S. Senator would say, 
"Bring...It...On!"  :-D

You'd have to look at your vmstat as well as top, of course, and check 
out your load, but my suspicion is that DRAM will also help you.  OO.o 
is a bit memory-hungry, and if you're using the default GNOME desktop, 
you could be staring 100MB/student DRAM usage in the face.  Note that 
GNU/Linux will use up all your available DRAM for things like file 
caching, so, as Les Mikesell has said before, vmstat is definitely your 
friend here (look for a lot of swapping).

As for TuxType, that application will suck up 73Mb/session in a 
heartbeat.  So, if you're running 100BaseTX on your server, you can 
imagine what that'll do.  If you're running that application, or 
anything else like it (TuxMath, Chromium B.S.U., etc.), better have 
Gig-E on the server, and if your hardware supports it, have two Gig-E 
NICs and try to gang 'em together.

--TP
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