[K12OSN] performance issues

[Kanwar Ranbir Sandhu]

On Wed, 2006-03-05 at 03:03 -0500, Liam Marshall wrote:
> I have a dual zeon 3.06 GHz server, currently with 4 80 Gb SATA drives 
> connected to a MegaRaid 4 port raid controller set for raid 0.  I have 
> currently 2 Gb of RAM.

Why are you using RAID 0?  RAID 0 gives tremendous speed, but there
isn't any fault tolerance.  RAID 1, or even RAID 5, would be a much
better option.  

I personally have never recommended or implemented SATA drives in Linux
terminal servers.  I just don't trust SATA drivers enough to put them
in.  I prefer using SCSI 15K RPM drives - not sure if SATA drives are
available at that speed.

At 2 GB of RAM for 30 users, you're probably on or over the threshold of
swapping to disk.  That's usually BAD on a Linux terminal server.

Other than that, your hardware looks fine.

> Workstations are almost exclusively IBM 300PLs which are thin clients, 
> onboard video, sound, nic, etc

That looks good.  You mention 96MB in the thin client further down in
your message - that's more than enough.

> They are a little slow when 30+ workstations all load StarOffice 7 at 
> the same time, or when they log out.

That's a massive load.  That being said, a properly configured server
should be able to handle that fairly well.  For example:

- stop all non-essential services
- fast disks (at least 10K RPM, 15K RPM is better)
- zero to minimal swapping
- enough RAM (at least 50 MB per user + 500 MB for the distro)

> I am planning on upgrading memory from 2 to 4 Gb, and increase the 
> backbone to Gb, but this upgrade will most likely not happen till 
> summer.

The RAM upgrade will help, most certainly.

> In the mean time, is there anything I can do to increase 
> performance?  Non of the workstations have hard drives, and their memory 
> is 96 Mb each.  I have tried enabling swapfiles with not much 
> perceivable difference.

I think your bottleneck is:

- RAM
- slow disks
- too much load

You could investigate with any number of tools, such as vmstat.  Fire up
all 30 thin clients and have them load StarOffice.  Watch vmstat while
all that is going on - you'll quickly see where your problems lie.

> What is the deal with running apps locally?  
> And how do I/Can I do it?

You run an app, such as Firefox, on the thin client.  It's a great way
to take some load off the server, yet still be able to manage thin
clients from one location.  The caveat is the thin client has to be
powerful enough to run the application.  In your case, you'll have to
upgrade the RAM to at least 128MB.  The CPU might be too slow - not
sure.

<rant>
I've never liked setting up local apps with LTSP.  It used to be too
much of a pain in the butt.  Recently, I think it's been made easier.
Though, I haven't tried in a couple of years.

I find that another Linux thin client project, Thinstation, handles this
much better.  Actually, I now prefer Thinstation over LTSP, period.  I
stopped using and recommending LTSP to clients in the first half of 2005
after spending a lot of time looking into Thinstation.
</rant>

Anyway, I hope this was of some help.

Regards,

Ranbir
-- 
Kanwar Ranbir Sandhu
Linux 2.6.16-1.2096_FC4 i686 GNU/Linux 
11:45:29 up 5:15, 3 users, load average: 0.18, 0.19, 0.18