[K12OSN] $5,000 cluster server powers 120 clients?

[Petre Scheie]

Depends on what you mean by 'cluster'.  If you're talking about using OpenMosix 
to cluster them, then no, I don't think it's a good approach.  We had some 
discussion of this a while back, and the problem is getting applications to 
migrate from one server to another as needed; in short, it doesn't work with 
things like Mozilla & OpenOffice.

The approach that I think makes the most sense is to use one or two servers for 
just providing the KDE/Gnome/IceWM environment, and then dedicating the other 
servers to one or two applications, ultimately with one app per server.  That 
way, pigs like OOo don't affect the performance of lighter faster apps.  Also, 
to upgrade an app, you just get it going on a new server, once it's ready, you 
change the link on the users' menus/desktops, and there's no downtime.

The proof-in-the-pudding for this approach is Largo, FL, where they use this 
exact approach.  Doing so allows them to support 240 users with a couple of 
900mhz terminal servers.  They found they could get the per-user memory 
consumption down to about 13M and I think that was using KDE. (They don't use 
LTSP, preferring to roll their own terminal servers.)  Also, with this approach, 
you spend money only on the apps that need a lot of resources, e.g. more memory 
for those apps that need it.  It also scales up better because for each 
additional app that you add, you just add another server.  But, if money is 
tight, and, say, you can only afford four app servers but you have 16 apps, you 
can put multiple apps on each server, for an average of 4 apps/server, and then 
next year get just one more server, move some apps to that new server (probably 
a newer version of the app in question), for an average of 3.2 apps/server and 
repeat in the years after that.  In some cases those servers may not even need 
to be that big, depending on the apps.

Petre

Robert Arkiletian wrote:
> 
> I think this idea is worth looking at:
> 
> Why not make a MONSTER LTSP server with say a 6 node cluster of AMD 
> Sempron 3100+'s. They have built in memory controller so RAM latency is 
> low. They are 754 pin cpu and most of these MB come with Gigabit lan and 
> SATA built in. Here is the specs for each node:
> 
> CPU AMD Sempron 3100+ (32bit cpu) $150
> MB ASUS K8V-X VIA K8T800 (or nforce3 chipset)  Gigabit LAN, SATA $120
> Ram 2 sticks of 1024MB= 2GB DDR400  $220
> HD 1 Seagate SATA 120GB   $120
> case with quality 400W PS $100
> 
> Total cost of 1 node approx. $700
> Cluster price approx. $4200 + Plus Switch for cluster: 8 port gigabit 
> switch $200 = $4400 total
> (approx. same price as a dual Xeon 2.8Ghz with 4Gb of RAM)
> 
> But this 6 node cluster would be at least 10x more powerful.
> 720 GB disk storage
> 12 GB RAM
> Could serve 120 clients == 4 labs
> 
> What do you guys think?
> 
> Robert Arkiletian
> Eric Hamber Secondary School
> 
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