[Server-devel] Latest on capacity of the school server

[Martin Langhoff]

On Thu, Jul 1, 2010 at 1:45 PM, David Leeming
<david at leeming-consulting.com> wrote:
> What experience do we have on the latest thinking about the capacity of a
> single server? Here in Kosrae they have good 24/7 power availability and
> air-conditioned offices in five of the schools. We can therefore specify
> powerful machines, even dedicated server models if need be.  If we segregate
> off each of the 24 class groups, would a single powerful machine server be
> able to handle 500 students in 24 classes (courses) simultaneously? (of
> course in practice that maximum load will rarely occur).

The XS will be ok. Add RAM (webapps and proxy are memory-bound) and a large HD.

What *will* melt with 500 active users is the WiFi infra.

> floors, 12 classrooms per floor, in U-shape layout. I would place one AP per
> classroom spread evenly around the school – that would be about 20 students
> per AP. The APs set up all on eth1 LAN with the same SSID. If we use
> multiple servers, we’d use different SSIDs for each. I have not deployed
> such a large site before so any comments on this would be appreciated.

One AP per 20 is more than good. We've seen some good APs handle 40~50
(with modest traffic).

Do NOT go for multiple servers. Therein lies madness.

> In PNG SDP’s project in North Fly, PNG, we are using small “eboxes” because
> of the need to run on solar power. We have deployed one full-campus
> wireless/server installation, quite a small school (160 total, 80 users in
> the first roll out). These users are divided into 3 class groups, as Moodle
> courses. So they are segregated. We have had feedback that it still gets
> slow / congested when all users are on simultaneously (80 users in 3
> separate courses).

Interesting. Ask them for a day and time when it was sliggush within
the last couple of weeks. sysstat is running on the XS. Look at the
/var/log/sa/sar* files (or  call the 'sar' command for today's output)
. It keeps approx 1 month IIRC. Filenames end with the
'day-of-the-month' number.

> I don’t have an opportunity to visit the school and

Damn - anyone with the skills to find those files for you?

cheers,


m
-- 
 martin.langhoff at gmail.com
 martin at laptop.org -- School Server Architect
 - ask interesting questions
 - don't get distracted with shiny stuff  - working code first
 - http://wiki.laptop.org/go/User:Martinlanghoff