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

[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 <bryan at 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 <bryan at 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  
>>>>> <bryan at 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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