On Thu, Sep 04, 2008 at 05:55:26PM +0100, Garry Saddington wrote:
<snip>
OK, so I've got (so far) 90 students / 3 servers = 30 students a server.
8000M - 512M(for the server bits) / 30 = ~250M per student, ram requirements.
So, lets go forward with these rough calculations.
> log on times in the order of 4-8 minutes, some not even managing it.
OK, we need to quantify this a little better. Assuming 30 students per server,
at what point does it start to bog down? Can 1 user log in successfully, and
start up firefox? 2? 4? 8? We need to find where the breaking point is.
I've noticed (myself) that the new firefox 3 seems to be more efficient on the
CLIENT's memory use, but seems to use MORE server ram. How much swap space do
you have configured? The old sysadmin's saw of "double the swap for the amount
of ram in the box" means you should have AT LEAST 16 gigs of swap allocated on
disk. If you stuck with Ubuntu's default 3 gig, you'd find yourself in trouble
fairly quickly.
Start by testing having people ramp up the number of concurrent logins, and see
(either using the 'top' command or the 'free' command) what happens to your ram
and swap. Another good, graphical utility I like is xosview.
>Firefox
> refusing to start for an entire class except one student.
Do you have shared home directories? NFS issue? You don't have everyone
logging in as the same userid, do you?
> Load values of 12
> and more with cpu's at less than 50% usage.
This indicates to me that you're IO bound, and, my suspicion, swapping, or more
probably, running out of swap.
> USB storage access broken.
No indication here WHAT's broken, so I can't help you.
> I have
> never seen an LTSP install so slow. Virtually unworkable in a teaching
> environment. Bare in mind that the only thing that changed was the OS and
> LTSP version.
I'll snip the rest, but you seem to indicate you've been running it for 7
years. What kind of terminals do you have? What version of LTSP? What
version of the host OS?
We're going to need a lot more info, if we're to help you.
I know things are capable of working, since here's one of my servers on Hardy:
[EMAIL PROTECTED]:~# uptime
09:07:34 up 2 days, 11:51, 35 users, load average: 1.20, 1.23, 0.97
[EMAIL PROTECTED]:~# free
total used free shared buffers cached
Mem: 8308360 5929988 2378372 0 79552 1670116
-/+ buffers/cache: 4180320 4128040
Swap: 11344520 104160 11240360
[EMAIL PROTECTED]:~# ps -ef | grep firefox | wc
23 187 1888
Now, I haven't got quite 30 users running firefox, but I've got 23. Here's the
interesting statistic:
14642 noyb1 20 0 155m 53m 20m S 22 0.7 0:04.64 firefox
15287 noyb2 20 0 153m 53m 21m S 7 0.7 0:07.24 firefox
10037 noyb3 20 0 192m 78m 23m S 6 1.0 0:21.81 firefox
15312 noyb4 20 0 149m 64m 20m S 6 0.8 0:10.17 firefox
12789 noyb5 20 0 165m 89m 20m S 4 1.1 0:17.47 firefox
It's early in the morning here, so the browsers haven't been up for too long,
but remember how we've only got around 250M per user? You've got (on a
thumbnail average) ~175 megs being used up per user here on firefox alone.
If you're running an older server OS, with older versions of everything, then I
think you're going to find that more ram's needed now.
Cheers,
Scott
--
Scott L. Balneaves | "There are many causes I am prepared to die for,
Systems Department | but no causes I am prepared to kill for."
Legal Aid Manitoba | -- Mohandas Karamchand Gandhi
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