[K12OSN] Large scale implementation in the pipe, input needed.

[Josiah Ritchie]

If you want it to go right, your main concern is dependability and
flexibility. If things at your place are anything like here, the odds of
clearly understanding the need and realistically expecting growth are
low. Therefore, I'd say you need something flexible. That means a server
in each school able to handle twice the current desires (and more than
twice if possible). However, for flexibility, I'd plan on a central NFS
directory and Authentication database (LDAP is best IMHO).

The important information that needs to be protected is home directories
and user database. Having that in a central location would be
worthwhile. Replacing this information is very difficult. Getting a new
LTSP server up and running is easy and trivial. In fact, once you have
the first one it's easy to replicate it across machines and things on
the servers won't need to change much. (It's like using Ghost for your
desktops.) Having one server out of five go down is much less of a
problem then having "THE" server go down. hardware will almost certainly
fail eventually.

I'm not sure, but the bandwidth concerns of a 1Gig connection to that
many clients that also has to share the environment with many other
computers using other programs could easily become congested if they are
doing more than surfing websites, but rather accessing internal network
resources.

Anyway to sum up:
* Less demanding of bandwidth (keeps things fast)
* Quickly replaceable LTSP servers
* Central storage of irreplacable data
* Easy backup of important data
* Very Flexible expansion to other environments
* LDAP makes managing users easier and more powerful (IMHO)
* LDAP allows for expansion of services based on your userbase
  (for example: email, authenticated web filtering, intranet sites,
  webmail, etc.)

It might work using NFS for various parts of the servers directory like
/etc maybe so that you can be sure that all your machines are kept with
the same configs and make fixing one problem with fix it on all if it's
a config issue. That would get you the benefit of a central server with
the flexibility of a distributed environment. If I did this I'd want to
have one main NFS server that acted as a backup LDAP server and one LDAP
server that acted as a backup NFS server. LDAP can replicate info
immediately through slurpd and I'd replicate the data from the main NFS
server to the backup one hourly using rsync. Rsync only sends changes
and therefore wouldn't be a large bandwidth hog, but still keep things
in good shape. (Note: This is not a file backup solution cause files
deleted will be gone from both servers in an hour and your users won't
like that at all. :-)

I think I just NSF'd my $.02 :-)

JSR/

On Thu, 2004-08-19 at 17:34, Daniel Hedblom wrote:
> Hi!
> 
> At the school district im an admin at there are talks about implementing a
> large scale k12 LTSP solution. We have been testing succesfully on one
> school but only with about 15 clients. The latest bid is to have one big
> central server. It will be serving a cuple of other schools over 1 gbit
> fiber connections. An estimate over the number of clients would be about
> 50-60 at two schools and maybe 40 additional from other smaller schools
> and locations.
> 
> I have been pondering this quite a bit and im a bit concerned about the
> cost of the server and backbones etc. Since other traffic flows in the
> same fibers there will have to be some kind of vlan separating the traffic
> since passwords etc flows unencrypted between client/server. I really
> would appriciate input on this since i have a thing for linux and wouldnt
> want an implementation to go wrong at my own turf. Is a central server a
> good solution or is the benefit smaller than percieved? Have anyone done
> this in a grand scale and what was the pitfalls in those cases?
> 
> Im perticulary interested in how scaling have been solved on big sites.
> Have tried an openmosix cluster but the benefit was small since we dont
> run any cpu intensive applications.
> 
> In short, is it a good solution to get a big iron hosting everything
> instead of spreading several smaller Terminal Servers onsite and just
> centralize /home and logins?
> 
> All inputs are appriciated.
> 
> Cheers!
> 
> /daniel
> 
> 
> 
> 
> 
> 
> 
> 
> 
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-- 
Josiah Ritchie
Network Administrator
Washington Bible College
Capital Bible Seminary