Re: [Server-devel] Serving 400+ students w/ a single central XS - ejabberd nightmare?

2009-03-15 Thread Martin Langhoff
On Wed, Mar 11, 2009 at 5:54 PM, John Watlington w...@laptop.org wrote:
 If you aren't going to place school servers in the actual schools,
 and insist on
 centralizing them, the hardware recommended by Sameer is a good idea.

+1 -- also, Dev Moharty's suggestion is good: run one XS for each
school in your central location. If you have one big honking box, you
could virtualise things (but I don't particularly recommend it).

cheers,



m
-- 
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 mar...@laptop.org -- School Server Architect
 - ask interesting questions
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Re: [Server-devel] Serving 400+ students w/ a single central XS - ejabberd nightmare?

2009-03-10 Thread Reuben K. Caron

Daniel Drake wrote:

2009/3/9 Bryan Berry br...@olenepal.org:
  

We will have roughly 8+ AP's. We have found that off-the-shelf AP's can
handle around 60-70 users.  But that doesn't still doesn't solve the
problem of the XO's getting bogged down by tons of ejabberd chatter.

DSD: do you have any ideas about this?



Have only had a chance to test numbers on Linksys WRT54Gsomething
routers, which stop accepting new connections after 33 users. yay.
  

Have you tried loading a different firmware on these, dd-wrt?
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Re: [Server-devel] Serving 400+ students w/ a single central XS - ejabberd nightmare?

2009-03-10 Thread Rangan Srikhanta
Folks,

 

Here at OLPC AU, we are using Linksys WRT54GLs using DD-WRT and configuring
the routers to act as an AP according to the following instructions.
http://www.dd-wrt.com/wiki/index.php/Wireless_Access_Point 

 

I found I could turn the WRT54GL into the required AP mode in 10minutes,
using an XO. 

 

In our first round of deployments we will be only using WRT54GLs, and after
speaking to Dev, will be working on 1 for every 25. 

 

Thx,

 

Rangan

 

From: server-devel-boun...@lists.laptop.org
[mailto:server-devel-boun...@lists.laptop.org] On Behalf Of Reuben K. Caron
Sent: Tuesday, 10 March 2009 11:29 PM
To: Daniel Drake
Cc: server-devel
Subject: Re: [Server-devel] Serving 400+ students w/ a single central XS -
ejabberd nightmare?

 

Daniel Drake wrote: 

2009/3/9 Bryan Berry  mailto:br...@olenepal.org br...@olenepal.org:
  

We will have roughly 8+ AP's. We have found that off-the-shelf AP's can
handle around 60-70 users.  But that doesn't still doesn't solve the
problem of the XO's getting bogged down by tons of ejabberd chatter.
 
DSD: do you have any ideas about this?


 
Have only had a chance to test numbers on Linksys WRT54Gsomething
routers, which stop accepting new connections after 33 users. yay.
  

Have you tried loading a different firmware on these, dd-wrt?

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Re: [Server-devel] Serving 400+ students w/ a single central XS - ejabberd nightmare?

2009-03-10 Thread Dev Mohanty
Rangan,

I remember the Linksys routers used to drop connection, as soon as 33-34
clients were logged in, and as Bryan
mentioned we got much better perfomance with the readily available
Taiwanese brand
of APs. With a Linksys 25 odd clients works just fine though with heavy
traffic.

With the Linksys WRT54G /L/S variants, its important to note the version (eg
5.1/ v6/ v8) and chip used (Atheros/ Broadcom) as
only certain versions support full funtionality, with opensourced firware.

Here's a good table to refer to:
http://www.dd-wrt.com/wiki/index.php/Supported_Devices

Cheers,
Dev


On 3/10/09, Rangan Srikhanta ran...@laptop.org.au wrote:

 Folks,



 Here at OLPC AU, we are using Linksys WRT54GLs using DD-WRT and configuring
 the routers to act as an AP according to the following instructions.
 http://www.dd-wrt.com/wiki/index.php/Wireless_Access_Point



 I found I could turn the WRT54GL into the required AP mode in 10minutes,
 using an XO.



 In our first round of deployments we will be only using WRT54GLs, and after
 speaking to Dev, will be working on 1 for every 25.



 Thx,



 Rangan



 *From:* server-devel-boun...@lists.laptop.org [mailto:
 server-devel-boun...@lists.laptop.org] *On Behalf Of *Reuben K. Caron
 *Sent:* Tuesday, 10 March 2009 11:29 PM
 *To:* Daniel Drake
 *Cc:* server-devel
 *Subject:* Re: [Server-devel] Serving 400+ students w/ a single central XS
 - ejabberd nightmare?



 Daniel Drake wrote:

 2009/3/9 Bryan Berry br...@olenepal.org br...@olenepal.org:



 We will have roughly 8+ AP's. We have found that off-the-shelf AP's can

 handle around 60-70 users.  But that doesn't still doesn't solve the

 problem of the XO's getting bogged down by tons of ejabberd chatter.



 DSD: do you have any ideas about this?





 Have only had a chance to test numbers on Linksys WRT54Gsomething

 routers, which stop accepting new connections after 33 users. yay.



 Have you tried loading a different firmware on these, dd-wrt?

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Re: [Server-devel] Serving 400+ students w/ a single central XS - ejabberd nightmare?

2009-03-10 Thread Sameer Verma
On Tue, Mar 10, 2009 at 6:14 AM, Daniel Drake d...@laptop.org wrote:
 2009/3/10 Reuben K. Caron reu...@laptop.org:
 Have you tried loading a different firmware on these, dd-wrt?

 No, but there are regulatory issues there and we won't be using them
 in the schools...only used them because it was the only thing
 available to run tests with.

 The exact model is Linksys WRT54Gv8. You'd think that after 8
 revisions and several years of developing these APs might support 34
 users, WDS, or running as a STA. nope!


There's a reason why Cisco bought them. Upgrade path! Squeeze from
below, pull from above. http://www.linksystocisco.com/

Sameer

 Daniel
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Re: [Server-devel] Serving 400+ students w/ a single central XS - ejabberd nightmare?

2009-03-10 Thread John Watlington

If you aren't going to place school servers in the actual schools,  
and insist on
centralizing them, the hardware recommended by Sameer is a good idea.

My argument has always been that you want local web caching and content,
and that an XS shouldn't be that much more expensive than the above  
hardware.
If you are willing to guarantee constant connectivity to a central  
office to support
centralized servers, remotely maintaining the servers in the schools  
shouldn't be a problem.

Cheers,
wad

On Mar 10, 2009, at 1:57 PM, Sameer Verma wrote:

 On Tue, Mar 10, 2009 at 3:12 AM, Bryan Berry br...@olenepal.org  
 wrote:
 On Mon, 2009-03-09 at 21:51 -0700, Sameer Verma wrote:
 On Mon, Mar 9, 2009 at 7:04 PM, Bryan Berry br...@olenepal.org  
 wrote:
 On Tue, 2009-03-10 at 09:58 +1300, Martin Langhoff wrote:
 On Mon, Mar 9, 2009 at 12:11 AM, Bryan Berry  
 br...@olenepal.org wrote:
 I am worried about the XO's and not the XS.

 Now you're starting to see what I've seen :-/ I also worry  
 about your
 APs and networking infra -- to support 400 active users you'll  
 want at
 least 8 APs. In more realistic terms, you'll probably need 12,
 assuming a reasonably balanced load.

 We will have roughly 8+ AP's. We have found that off-the-shelf  
 AP's can
 handle around 60-70 users.  But that doesn't still doesn't solve  
 the
 problem of the XO's getting bogged down by tons of ejabberd  
 chatter.

 DSD: do you have any ideas about this?

 We are looking at about 100-150 students per school and  
 connecting 3-4
 schools to a central XS.

 As I mentioned before... I am working on xs-0.6, with the
 moodle-ejabberd magic.

 That's great, but our pilot starts in a month but that doesn't  
 fit our
 timeline. I don't want to send out a completely new, untested XS  
 into
 rural parts of Nepal.

 Do you have any other suggestions fo us?


 What if you had a small footprint box (like a soekris or  
 routerboard)
 at the school that talks to APs on one end via a switch, and does
 tunneling back to XS in a central location? That way you would  
 have a
 fairly dumb tunnel unit at school (literally plug-and-play) and XS
 management back at your central shop.

 Sameer

 Thanks for the suggestion Sameer.

 I don't really understand what benifits the soekris or routerboard  
 adds
 in this situation? Can u pls explain further?


 The Soekris unit (say Soekris 4501 http://www.soekris.com/net4501.htm)
 would sit at the school location talking to the APs via a switch on
 one end and create a tunnel on the other end to your XS farm. The
 tunnel runs over a VPN from school to XS farm. Both Soekris and
 Routerboard have miniPCI slots that will take hardware accelerators
 for VPN such as this one: http://www.soekris.com/vpn1401.htm so it is
 possible to run VPNs on these boards.

 Soekris units are almost zero maintenance (no moving parts etc.) and
 can also double up as APs. One thing to note: the hw VPN accelerator
 support under Linux isn't very robust. I've used it with BSD
 (http://m0n0.ch/wall/) and it works well. It will do IPSec VPN
 tunnels. http://m0n0.ch/wall/features.php

 With a zero maintenance small footprint unit at the school (will run
 with 12 V as well) and XS units at your school server farm you can
 maintain the XS units locally and keep the school network running via
 the VPN.

 The last time I suggested this, the -1 reasoning was that you would
 need a good connection between the school and the XS farm.
 http://lists.laptop.org/pipermail/server-devel/2008-October/ 
 002244.html

 Sameer
 -- 
 Dr. Sameer Verma, Ph.D.
 Associate Professor of Information Systems
 San Francisco State University
 San Francisco CA 94132 USA
 http://verma.sfsu.edu/
 http://opensource.sfsu.edu/ole-nepal- 
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Re: [Server-devel] Serving 400+ students w/ a single central XS - ejabberd nightmare?

2009-03-09 Thread Bryan Berry
On Tue, 2009-03-10 at 09:58 +1300, Martin Langhoff wrote:
 On Mon, Mar 9, 2009 at 12:11 AM, Bryan Berry br...@olenepal.org wrote:
  I am worried about the XO's and not the XS.
 
 Now you're starting to see what I've seen :-/ I also worry about your
 APs and networking infra -- to support 400 active users you'll want at
 least 8 APs. In more realistic terms, you'll probably need 12,
 assuming a reasonably balanced load.

We will have roughly 8+ AP's. We have found that off-the-shelf AP's can
handle around 60-70 users.  But that doesn't still doesn't solve the
problem of the XO's getting bogged down by tons of ejabberd chatter.

DSD: do you have any ideas about this?

We are looking at about 100-150 students per school and connecting 3-4
schools to a central XS. 

 As I mentioned before... I am working on xs-0.6, with the
 moodle-ejabberd magic.

That's great, but our pilot starts in a month but that doesn't fit our
timeline. I don't want to send out a completely new, untested XS into
rural parts of Nepal.

Do you have any other suggestions fo us?

  This dell server has a dual-core Xeon 3.0 GHz processor and 2 GB RAM.
  RAM was fine, beam only used 450 MB according to ps_mem.py
 
 Well, that's 1/4 of your RAM. You need to budget for apache/php,
 postgres, and squid. Right now the main problem is Squid.

That was 450 MB during account creation. It dropped significantly
thereafter. I didn't provide much server stats last time because the XS
resource usage isn't a critical problem.

 Thanks for the list below. Quite a few are about stuff I can't help
 with (roof leaks, power cords...) the others, I'm working on...

That's the whole point of why I am telling you about such problems and
how they make a centralized XS easier for us to maintain.


-- 
Bryan W. Berry
Technology Director
OLE Nepal, http://www.olenepal.org

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Re: [Server-devel] Serving 400+ students w/ a single central XS - ejabberd nightmare?

2009-03-09 Thread Daniel Drake
2009/3/9 Bryan Berry br...@olenepal.org:
 We will have roughly 8+ AP's. We have found that off-the-shelf AP's can
 handle around 60-70 users.  But that doesn't still doesn't solve the
 problem of the XO's getting bogged down by tons of ejabberd chatter.

 DSD: do you have any ideas about this?

Have only had a chance to test numbers on Linksys WRT54Gsomething
routers, which stop accepting new connections after 33 users. yay.

I haven't seen XO's bogged down by ejabberd chatter. Ran 75 today
while monitoring the TX/RX stats on the LAN interface on the XS and
was impressed at how low it was.

Yes, the XOs run slow when you view a busy neighborhood view, but it's
fine as soon as you switch away. There was a bug where sugar updates
every icon on the neighborhood view 10 times every second when you are
on that screen (but only when you are on that screen), it's fixed for
0.84.

 That's great, but our pilot starts in a month but that doesn't fit our
 timeline. I don't want to send out a completely new, untested XS into
 rural parts of Nepal.

I tried and didn't get any feedback from XS usage in large
deployments, so we pretty much figured we'd send it into not-as-rural
paraguay and find out what happens (we don't really have any other
options!).

Daniel
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Re: [Server-devel] Serving 400+ students w/ a single central XS - ejabberd nightmare?

2009-03-09 Thread Bryan Berry
On Mon, 2009-03-09 at 22:36 -0400, Daniel Drake wrote:
 2009/3/9 Bryan Berry br...@olenepal.org:
  We will have roughly 8+ AP's. We have found that off-the-shelf AP's can
  handle around 60-70 users.  But that doesn't still doesn't solve the
  problem of the XO's getting bogged down by tons of ejabberd chatter.
 
  DSD: do you have any ideas about this?
 
 Have only had a chance to test numbers on Linksys WRT54Gsomething
 routers, which stop accepting new connections after 33 users. yay.

The linksys is WRT54G total crap. We don't use them. We have found that
cheaper AP's do much better. We have good luck w/ random Taiwanese
brands like Compex, Lantech, and AZTech. They have Atheros or RealTek
chipsets

 I haven't seen XO's bogged down by ejabberd chatter. Ran 75 today
 while monitoring the TX/RX stats on the LAN interface on the XS and
 was impressed at how low it was.
 
 Yes, the XOs run slow when you view a busy neighborhood view, but it's
 fine as soon as you switch away. There was a bug where sugar updates
 every icon on the neighborhood view 10 times every second when you are
 on that screen (but only when you are on that screen), it's fixed for
 0.84.

I saw it drop as well when I changed out of the Network View, but it
still remained fairly high w/ 200 very active users, too high to keep me
from launching EToys

  That's great, but our pilot starts in a month but that doesn't fit our
  timeline. I don't want to send out a completely new, untested XS into
  rural parts of Nepal.
 
 I tried and didn't get any feedback from XS usage in large
 deployments, so we pretty much figured we'd send it into not-as-rural
 paraguay and find out what happens (we don't really have any other
 options!).
 
 Daniel

I think that is because large deployments like Uruguay aren't using the
XS and others like Mongolia don't have the technical expertise to
monitor such things.

That leaves new large deployments like Paraguay and Nepal in an
unenviable position as pioneers.

-- 
Bryan W. Berry
Technology Director
OLE Nepal, http://www.olenepal.org

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Re: [Server-devel] Serving 400+ students w/ a single central XS - ejabberd nightmare?

2009-03-09 Thread Sameer Verma
On Mon, Mar 9, 2009 at 7:04 PM, Bryan Berry br...@olenepal.org wrote:
 On Tue, 2009-03-10 at 09:58 +1300, Martin Langhoff wrote:
 On Mon, Mar 9, 2009 at 12:11 AM, Bryan Berry br...@olenepal.org wrote:
  I am worried about the XO's and not the XS.

 Now you're starting to see what I've seen :-/ I also worry about your
 APs and networking infra -- to support 400 active users you'll want at
 least 8 APs. In more realistic terms, you'll probably need 12,
 assuming a reasonably balanced load.

 We will have roughly 8+ AP's. We have found that off-the-shelf AP's can
 handle around 60-70 users.  But that doesn't still doesn't solve the
 problem of the XO's getting bogged down by tons of ejabberd chatter.

 DSD: do you have any ideas about this?

 We are looking at about 100-150 students per school and connecting 3-4
 schools to a central XS.

 As I mentioned before... I am working on xs-0.6, with the
 moodle-ejabberd magic.

 That's great, but our pilot starts in a month but that doesn't fit our
 timeline. I don't want to send out a completely new, untested XS into
 rural parts of Nepal.

 Do you have any other suggestions fo us?


What if you had a small footprint box (like a soekris or routerboard)
at the school that talks to APs on one end via a switch, and does
tunneling back to XS in a central location? That way you would have a
fairly dumb tunnel unit at school (literally plug-and-play) and XS
management back at your central shop.

Sameer
-- 
Dr. Sameer Verma, Ph.D.
Associate Professor of Information Systems
San Francisco State University
San Francisco CA 94132 USA
http://verma.sfsu.edu/
http://opensource.sfsu.edu/

  This dell server has a dual-core Xeon 3.0 GHz processor and 2 GB RAM.
  RAM was fine, beam only used 450 MB according to ps_mem.py

 Well, that's 1/4 of your RAM. You need to budget for apache/php,
 postgres, and squid. Right now the main problem is Squid.

 That was 450 MB during account creation. It dropped significantly
 thereafter. I didn't provide much server stats last time because the XS
 resource usage isn't a critical problem.

 Thanks for the list below. Quite a few are about stuff I can't help
 with (roof leaks, power cords...) the others, I'm working on...

 That's the whole point of why I am telling you about such problems and
 how they make a centralized XS easier for us to maintain.


 --
 Bryan W. Berry
 Technology Director
 OLE Nepal, http://www.olenepal.org

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Re: [Server-devel] Serving 400+ students w/ a single central XS - ejabberd nightmare?

2009-03-08 Thread Martin Langhoff
On Sun, Mar 8, 2009 at 7:52 PM, Bryan Berry br...@olenepal.org wrote:
 But 200-300 users could be online at once. I think it will be too
 complicated to tell some of them: Don't connect to the AP right now,
 you may overwhelm ejabberd

Give ejabberd enough RAM and it won't be a problem. The rest of your
infrastructure will, however.


 The XS is quite a complicated ensemble of software having an XS at every
 school magnifies the administration work.

What admin work do you foresee on the XS?

 Additionally our schools only have about 8 hours of electricity per day.
 I am concerned about the XS losing power suddenly multiple times per
 day.

Good point. I've been building everything with daily poweroffs in
mind and every component should handle it. But haven't field-tested...

 we can provide that (RAM)

Have you go the 4GB barrier in mind? Past 4GB we get into all sorts of
problems. You'll need a 64-bit machine, and you'll have to convince me
or someone else to build a 64-bit XS iso rather than the vanilla
32-bit we're using now.

 We have a relatively low latency connection b/w the schools and the XS.

Low latency, high bandwidth and everyone in the same netblock? No
routers in the middle. That's what the XS assumes, in any case.

 the conclusion that Nepal has different requirements than some of the
 other pilot schools.

Everybody is a little bit special. By deviating from how the XS is
designed to be deployed, you will add mgmt work to workaround whatever
gotchas.

And you make the Nepal deployment less useful to me too :-(  -- you'll
probably have to setup routing and other things on the XS so that
you'll have to carefully debug it to ensure it's not your network
setup before reporting it here.

Naturally, it's your call to make. It looks to me like you're getting
into a tricky space with routing setup, potential 64-bit OS and other
curly issues. If the administrative workload you expect on the XS is
really big and tricky, then I'd agree with you...

(... but then, I'd like to know what's the big and tricky admin work
on the XS? my design principle that it should be
super-low-maintenance... )

cheers,



m
-- 
 martin.langh...@gmail.com
 mar...@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
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Re: [Server-devel] Serving 400+ students w/ a single central XS - ejabberd nightmare?

2009-03-08 Thread Bryan Berry
On Sun, 2009-03-08 at 22:36 +1300, Martin Langhoff wrote:
 On Sun, Mar 8, 2009 at 7:52 PM, Bryan Berry br...@olenepal.org wrote:
  But 200-300 users could be online at once. I think it will be too
  complicated to tell some of them: Don't connect to the AP right now,
  you may overwhelm ejabberd
 
 Give ejabberd enough RAM and it won't be a problem. The rest of your
 infrastructure will, however.

I am worried about the XO's and not the XS.

I used the hyperactivity program and got some unscientific results. I
simulated 200 users using the schoolserver constantly. The CPU of the XS
was very busy, staying near 100% usage during the account creation
period and then it leveled off. I didn't monitor it very closely after
that b/c ejabberd is not my chief concern

This dell server has a dual-core Xeon 3.0 GHz processor and 2 GB RAM.
RAM was fine, beam only used 450 MB according to ps_mem.py

sudo ./hyperactivity.py gabble schoolserver.schoolnet.gov.np 200

I ran hyperactivity from my regular dell laptop

My XO showed 200 users in the Network View and became very sluggish. Top
showed that 30-40% of CPU was taken up w/ handling the sugar-shell, the
program which manages the Network View. The dbusdaemon was using roughly
15-20% of the CPU. I tried to launch one our E-Paath flash activities
and it hung displaying the error message Unresponsive script. I tried
to launch EToys and it failed as well.


  The XS is quite a complicated ensemble of software having an XS at every
  school magnifies the administration work.
 
 What admin work do you foresee on the XS?

  * Making sure that ejabberd keeps running
  * Making sure that the school doesn't have roof leak directly
above the XS
  * Making sure the schools doesn't remove the power cord and use it
for something else
  * Make sure the school doesn't repurpose the UPS for the XS for
charging cell phones
  * make sure the XS doesn't get zapped by a sudden power surge
  * Making sure it is there 3 months later
  * Make sure that dansguardian, squid, dhcp stay up week after week

We don't have any problem gettting the kids to take care of the XO's but
we have a Hell of a time making sure they take care of the XS

  Additionally our schools only have about 8 hours of electricity per day.
  I am concerned about the XS losing power suddenly multiple times per
  day.
 
 Good point. I've been building everything with daily poweroffs in
 mind and every component should handle it. But haven't field-tested...

Sadly, no one has and this is one of my chief concerns

  we can provide that (RAM)
 
 Have you go the 4GB barrier in mind? Past 4GB we get into all sorts of
 problems. You'll need a 64-bit machine, and you'll have to convince me
 or someone else to build a 64-bit XS iso rather than the vanilla
 32-bit we're using now.
 
  We have a relatively low latency connection b/w the schools and the XS.
 
 Low latency, high bandwidth and everyone in the same netblock? No
 routers in the middle. That's what the XS assumes, in any case.
 
  the conclusion that Nepal has different requirements than some of the
  other pilot schools.
 
 Everybody is a little bit special. By deviating from how the XS is
 designed to be deployed, you will add mgmt work to workaround whatever
 gotchas.




-- 
Bryan W. Berry
Technology Director
OLE Nepal, http://www.olenepal.org

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Re: [Server-devel] Serving 400+ students w/ a single central XS - ejabberd nightmare?

2009-03-08 Thread Dev Mohanty
Bryan I assume, this is in reference with the deployment planned at the
new schools, and guess am more then familiar with admin workload and
power limitations you
happen to mention in Nepal.

Hence was wondering if you've looked into the option of using more then one
XS, installed at the same location (eg DOE, OLE) if not at the
schools, this might make it a lot easier to administer. One XS could cater
to students in 3 schools while the other could register students/XOs from
the other two schools, for load balancing.. As am not too sure that using
additional RAM would get the desired results. And
ofcourse there's the 4GB RAM limitations on a 32bit processor, unless you
plan to use a PAE switch and tweak the kernel too and guess
that would be getting into murky waters.

Besides, as Martin pointed out using a 64bit processor would
require the XS iso to be completely
rebuilt, which might take a while forthcoming. Though, I've heard that
AMD's Athlon processors are backward
compatible with 32bit applications and permit use of more then 4GB RAM
without PAE, guess food for thought if you're adamant on using just one XS
for all the schools to reduce the overhead.

But still believe getting ejabberd to
perform with 400 simultaneous users, might still be a tough task.

Cheers,
Dev

On 3/8/09, Bryan Berry br...@olenepal.org wrote:

 On Sun, 2009-03-08 at 13:33 +1300, Martin Langhoff wrote:
  Bryan,
 
  I'm on the road, apologies if I'm a bit succint...
 
   - 400 users are unlikely to be online at the same time, supporting
  all users online at the same time will stress all the infra, so the
  path to success is, I suspect, paved with strategies to define usage
  patterns that avoid clustering everyone at the same time.


 But 200-300 users could be online at once. I think it will be too
 complicated to tell some of them: Don't connect to the AP right now,
 you may overwhelm ejabberd


   - I am working on 0.6 which will let you partition the school --
  instead of @online@, large schools can set moodle+ejabberd in a mode
  where users are in a shared-roster-group defined by their course
  membership in moodle. I've posted on the list and written in the wiki
  about this before if you need more detail.
 
   - More users - more RAM to the server :-) and disk space for backups

 we can provide that


   - Do you really have a low latency / high bw conn between the schools
  and the location with the XS? I have the feeling we had this
  conversation before... :-) and I suggested smaller and local, which is
  how the XS is designed to work. That's still my recommendation...


 The XS is quite a complicated ensemble of software having an XS at every
 school magnifies the administration work. Having a centralized XS for
 several schools can dramatically reduce administrative overhead.

 Additionally our schools only have about 8 hours of electricity per day.
 I am concerned about the XS losing power suddenly multiple times per
 day.

 We have a relatively low latency connection b/w the schools and the XS.

 We have discussed these issues before and I believe that we both came to
 the conclusion that Nepal has different requirements than some of the
 other pilot schools.


 --
 Bryan W. Berry
 Technology Director
 OLE Nepal, http://www.olenepal.org

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