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Re: [K12OSN] Servers, K12LTSP, and workstation numbers, etc.



Look into using application servers, that is, off-loading certain (or all) apps to dedicated servers. Five years ago, the City of Largo, FL was getting 240 users onto a pair of 900mhz dual CPU terminal servers by moving all the apps off of the TS onto dedicated servers; they carried it to its logical conclusion by devoting each app to its own server. When the user calls an app on another server, the traffic is just between the client and the app server, so you're not using up the bandwidth of the terminal server. This way if you find that, say, OOo is really hogging resources, you only have to find way to add a more hardware for that app, not the whole system. It's also easier for non-tech people to understand why you want more money to beef up the system when you can point to a particular app as being demanding.

There are other comprmises you can make to squeeze more users onto a given box: use IceWM instead of Gnome, Abiword instead of OOo Writer, etc. But if you really want to scale up, I think app servers are the route to go. If you NFS mount /home on the app boxes, you can do it all over SSH.

Petre

Doug Simpson wrote:
25 clients per server. . . we'd need about 40 servers. . .They'd never go for that. . . I was hoping to be able to serve hundreds per server. . .

Not a good deal, but. . .

Doug Simpson
Technology Specialist
DeQueen Public Schools
DeQueen, AR 71832
simpsond leopards k12 ar us
Tux for President!

On Mon, 24 Jul 2006, James P. Kinney III wrote:

It really boils down to networking at the Enterprise model level. Tests
have show that a 1Gb data line can support 25 clients.

RAM is still king as each client will need 50-75 MB of RAM.

We had about 56 clients hanging from a dual Opteron (single core) server
w/4GB RAM and dual, bonded Gb NICs. The load level was getting heavy but
OK until firefox got loaded. At that point, swap got hit and the box
thrashed itself into oblivion. A hard reboot later (and turning OFF
swap) and it _could_ run 56 clients but it was dragging.

So for the "Bottom dollar" person: a single chip, dual core w/ 2GB RAM
and 2 NICs (one Gb for clients, the other 100Mb for Internet) and a
120GB hard drive will serve 25+ clients very well. This a good model for
an "app server".

On Mon, 2006-07-24 at 10:15 -0500, Doug Simpson wrote:
Hello.

I finally have got my Superintendent excited about being able to use older hardware to save monty and use K12LTSP for thos older computers to make them usable again in Internet/Research/Writing labs in our schools.

I have several servers that have K12LTSP installed and ready to go, thinking I could run many workstations from them.

But when I read articles that say a district has 32 servers to deploy K12LTSP, I am thninking I am missing something because where is the cost savings in that, forst of all, and that means server updates and everything will have to be done on all those servers.

Our Supt. is a "Bottom Dollar" kind of guy and he doesn't look at TCO so much as what it will cost to "get it in the door".

Say I have a server with 12GB RAM, Almost a terabyte (sp?) of SCSI hard drive in Raid5 and Gigabit NICs. Realistically, how many workstations can I hang off there using Gnome, Mozilla, OOo, and several other apps on intermittent basis and see usable performance?

Also, I have one server, running FC1 with K12LTSP and it serves DHCP IP addresses, but I want another server to handle the terminals.

I added the next-server line to dhcpd.conf, but it still looks to the FC1 server to boot from. The other (preferred server) is FC3, K12LTSP and I think it is set up correctly.

What can I look for to make the workstations boot and run from the FC3 server with DHCP being handled by the FC1 server?

Thanks!

Doug Simpson
Technology Specialist
DeQueen Public Schools
DeQueen, AR 71832
simpsond leopards k12 ar us
Tux for President!

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James P. Kinney III          \Changing the mobile computing world/
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GPG ID: 829C6CA7 James P. Kinney III (M.S. Physics)
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