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"Joseph Hartman" 01-09-2008 11:50 PM

Advice on getting a computer lab server
 
Hello all,

I'm looking at purchasing a server for my school's multimedia lab to use with Edubuntu and LTSP. What are the minimum specs I should look for in a server that will power a lab with 35 P3 machines with 128MB RAM each? I teach elementary and middle school and will need the machines to be able to do all kinds of multimedia from editing movies to creating flash files to streaming video from the Internet.


Will two dual-core xeon processors do it for me or do I need to go quad core? (Does Ubuntu even support quad core processors at this time?)

How much RAM should I get and how much does Ubuntu support?


Should I just get 2 less powerful servers and split up the lab?

I'd prefer to have one server so I can have some control over the lab using the thin client manager, but it isn't a huge deal. Thanks for any advice. -joe


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Gavin McCullagh 01-10-2008 08:35 AM

Advice on getting a computer lab server
 
Hi,

On Wed, 09 Jan 2008, Joseph Hartman wrote:

> I'm looking at purchasing a server for my school's multimedia lab to use
> with Edubuntu and LTSP. What are the minimum specs I should look for in a
> server that will power a lab with 35 P3 machines with 128MB RAM each? I
> teach elementary and middle school and

First of all, in case you haven't, I'd suggest you try Edubuntu out with
some existing hardware before you launch into buying lots of hardware. You
presumably already have the thin clients, so maybe find a Pentium 3/4
somewhere with 512MB RAM, install edubuntu, and try one or two thin clients
on it (actually 256MB might be enough for a test). This means that when
you're ordering your hardware, there are less unknowns.

> will need the machines to be able to do all kinds of multimedia from
> editing movies to creating flash files to streaming video from the
> Internet.

What software will you use for these tasks? Have you tried them out
already? There is video editing software for Edubuntu, but it's probably
not as well developed as some other aspects (and to be honest, it's not
close to Final Cut Pro in most reviews I've seen).

http://www.linux.com/articles/60837
http://www.linux.com/feature/60624

I know there are some ways to create flash, but have you checked that
they're right for what you want? It would be interesting to hear your
findings.

> Will two dual-core xeon processors do it for me or do I need to go quad
> core?

For normal applications like web browsing, office, image editing etc. the
quantity of RAM is usually the thing that limits the number of clients.
4GB RAM should probably cover 35 users for those applications. CPU doesn't
usually limit this sort of stuff.

I've never seen an edubuntu cluster with 32 people doing video editing at
the same time. If they were all editing even moderately large video
content, I'd say you could run into problems with both RAM and CPU.

The next issue will be video playback. If a thin client plays a full
screen video, it gets rendered (from say, divx) on the server and sent as
raw video across the network to the thin client. That's 2 or 3 bytes per
pixel, about 1 million pixels per frame, 24 times per second (ignoring
sound) all of which must be sent over the network from the server to the
client in real time. That's a LOT of network traffic. If more than 5-10
users simultaneously watch full screen video on normal thin clients, even a
gigabit network will be in trouble.

To be honest, for any sort of intensive video applications, traditional
thin clients are not really suitable as the network traffic is too large.
A few youtube videos here and there will probably be fine, but a class
doing video editing may not be not realistic. If the thin clients ran the
video applications locally themselves that would be different, but that's
quite complicated to do and your thin clients probably don't have enough
RAM.

> (Does Ubuntu even support quad core processors at this time?)

I'm pretty sure this is no problem at all. linux supports multiple cores
and multiple cpus and has done for a long time.

> How much RAM should I get and how much does Ubuntu support?

Default 32-bit edubuntu supports up to 4GB (this is a limit of 32-bit
hardware) and with the -server- kernel can get at least up to 8GB. 64-bit
edubuntu supports so much more, you won't be need to worry about it.

2^32 = 4294967296 =~ 4GB
2^64 = 18446744073709551616

> Should I just get 2 less powerful servers and split up the lab?
>
> I'd prefer to have one server so I can have some control over the lab using
> the thin client manager, but it isn't a huge deal. Thanks for any advice.

An interesting question -- there are advantages in both.

If you had two servers and one went down (eg. hardware failure), it would
be nice that everyone could move over and work on the other, even in a
limited way. This should be a rare occurance though.

Having, say 2x quad cores on one machine gives all users access to 8
cores. Having 2x dual cores on two machines splits your users in half
giving each half 4 cores. If you get a burst of use on one half, the other
half is not in a position to help out and could be sitting idle. Also,
you'll have to use NFS and LDAP or NIS to make all users able to login on
both machines and see their home directories.

Price will also vary between the two options of course. The single big
server would probably draw less power and use the same or less space.

Either way, look into getting RAID (preferably RAID1), so that a disk
failure doesn't take your server down and consider a second power supply so
that a failed psu won't take it down either. Remember if your server dies,
every thin client dies with it.

Sorry if some of this has set you back a little, but you must be realistic
about video applications on thin clients before you spend lots of money.

Gavin


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"Joseph Hartman" 01-10-2008 10:37 PM

Advice on getting a computer lab server
 
Gavin, thanks for all the advice, it is immensly helpful. I actually started rolling out an edubuntu lab earlier this year and it became painfully clear early on that the server I have (3.0 GHz P4 Dell with 4GB Dual Channel DDR RAM) was not going to be adequate to handle all the thin clients. I have since dedicated my efforts towards setting up MiniLANs in each teacher's classroom with the P4 servers handling just 3 to 6 thin clients. This seems to be working alright, although things are still pretty slow. At least I don't have to worry about viruses any more though. To answer your question about software, my current curriculum for grades K-8 includes:

OpenOffice Impress, Writer, Calc, Scribus, Inkscape, GIMP, kturtle, Kompozer, Tuxtyping, Tuxpaint, and various Web 2.0 apps like Google Docs, Bubbl.us and Blogger.

I was hoping to use Kino and Blender with the middle schoolers at some point in the future, but it isn't a big deal to postpone those plans if need be.


Here's a few final questions if you don't mind.

In my current lab if I try to run more than about 7 thin clients they freeze up just playing flash games or running tuxtyping. Like I said, I have 4GB of Dual Channel DDR RAM so is the bottleneck with my 10/100 switch or my P4 CPU? Until now I've thought it was the CPU because when I look at the system monitor the CPU maxes out pretty quick. (maybe I should bring my c2d in from home and try it out to see how it holds up)


If I want to use the above programs and keep my current curriculum will a single server with 2 dual core xeons and 8 GB RAM be fast or just adequate? I want the lab to be fast. (obviously I'm just asking your opinion here)


Finally, what kind of switch should I get? Should I go all gigabit or is it enough to just be gigabit to the server and 10/100 to the clients? I do a lot of flash based reading games and stuff with the lower grades like
starfall.com and so I absolutely must have these activities perform well.

Thanks again Gavin, you've been extremely helpful. -joe


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Ian Mackenzie 01-10-2008 11:05 PM

Advice on getting a computer lab server
 
Joe wrote:



Here's a few final questions if you don't mind.



In my current
lab if I try to run more than about 7 thin clients they freeze up just
playing flash games or running tuxtyping. Like I said, I have 4GB of
Dual Channel DDR RAM so is the bottleneck with my 10/100 switch or my
P4 CPU? Until now I've thought it was the CPU because when I look at
the system monitor the CPU maxes out pretty quick. (maybe I should
bring my c2d in from home and try it out to see how it holds up)




If I want to use the above programs and keep my current
curriculum will a single server with 2 dual core xeons and 8 GB RAM be
fast or just adequate? I want the lab to be fast. (obviously I'm just
asking your opinion here)




Finally, what kind of switch should I get? Should I go all
gigabit or is it enough to just be gigabit to the server and 10/100 to
the clients? I do a lot of flash based reading games and stuff with the
lower grades like starfall.com and
so I absolutely must have these activities perform well.



--------------







(From
the Edubuntu web site) “If you have more than 10 users, it is
recommended to use gigabit ethernet for your LTSP servers. Although
normal usage ranges from 0.5 to 2mbit, clients can peak quite high
(70mbit), especially when watching multimedia content. “





So, gigabit from server -> switch and 100M from switch to client PCs
sounds about right. I"m about to build a core2Quad to serve the
computer lab, and see how it runs, and if there is room for expansion.



Ian Mackenzie



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Bill Moseley 01-11-2008 01:22 AM

Advice on getting a computer lab server
 
On Thu, Jan 10, 2008 at 03:37:12PM -0800, Joseph Hartman wrote:
> Gavin, thanks for all the advice, it is immensly helpful. I actually started
> rolling out an edubuntu lab earlier this year and it became painfully clear
> early on that the server I have (3.0 GHz P4 Dell with 4GB Dual Channel DDR
> RAM) was not going to be adequate to handle all the thin clients. I have
> since dedicated my efforts towards setting up MiniLANs in each teacher's
> classroom with the P4 servers handling just 3 to 6 thin clients. This seems
> to be working alright, although things are still pretty slow. At least I
> don't have to worry about viruses any more though. To answer your question
> about software, my current curriculum for grades K-8 includes:
> OpenOffice Impress, Writer, Calc, Scribus, Inkscape, GIMP, kturtle,
> Kompozer, Tuxtyping, Tuxpaint, and various Web 2.0 apps like Google Docs,
> Bubbl.us and Blogger.

Hi Joe,

Would you mind commenting a bit about how you are using the software
above at different grade levels? Do the programs you mention meet the
educational needs of the kids and teachers?

Is there software you miss from your old setup (I assume Windows since
you mention viruses).


> I was hoping to use Kino and Blender with the middle schoolers at some point
> in the future, but it isn't a big deal to postpone those plans if need be.

I'd hope that the savings from using ltsp would help buy a few nice
machines for video editing. Seems like a few nice iMacs would be a
nice addition.


--
Bill Moseley
moseley@hank.org


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"Joseph Hartman" 01-11-2008 06:10 AM

Advice on getting a computer lab server
 
Hi Bill,

The current curriculum has just undergone some recent changes in light of my beginning to teach middle school students in addition to elementary school students for the first time but I'd be happy to comment about the reasoning behind the current plan.


It arose out of specific school needs, state and professional organization standards (especially ISTE and Massachusettes since California doesn't have specific computer related technology standards), and my own experience/vision. The primary driving force towards Linux, LTSP, and Edubuntu arose out of necessity as much as anything else. I work at a charter school and we inherited a campus from a defunct public school complete with network and computers, the vast majority of the latter being from the wrong side of the millennium. Many of the machines we are using now were donated by organizations (the border patrol, district attorney's office, private companies, German Consulate) that were upgrading infrastructure and would otherwise have been discarded. Thus the ability to use these many underpowered and outdated machines as thin clients appealed to me. I'd guess we have about 200 workstations on campus altogether, of which about 50 are Pentium 4 and four are Core 2 Duo (the administrators' laptops and my own). The rest are P3, P2, or slower.


I should also mention that my school is an International Baccalaureate (IB) World School on the elementary side while the Middle School that just started up last year is in the accreditation process. Additionally, the elementary school operates under a German Immersion program that has the students spend one week learning in English under an English speaking teacher and the next week learning in German under a German speaking teacher. And the campus we inherited two years ago resides in a primarily Spanish-speaking and relatively underprivileged area of San Diego so our incoming students are rapidly changing the face of the school. All additional reasons to use the similarly multicultural and globally minded products of Ubuntu and GNU/Linux.


Because we are an IB school on the elementary side we have what is called a Program of Inquiry (POI) that is essentially a matrix of 6 big ideas per grade (so 36 big ideas total) that are divided up and taught throughout the year in addition (and hopefully in conjunction with) the normal classroom curriculum. POI topics are things like "objects in the sky move in predictable patterns" or "water is essential to life" and typically last for about 6 weeks. Thus my own curriculum assignments are designed around supporting these topics while at the same time teaching the students specific hard skills about the programs they are learning to use. I also try to collaborate with the teachers and their own projects as much as possible, although this is difficult since I only see each class for 45 minutes per week.


On to the curriculum....

In Kindergarten the students learn how to use a computer as many have never used one before or if they have it was for very specific tasks. Mouse practice, Tuxpaint, and learning about the parts of a computer pretty much sum it up, although I do try to collaborate with the teachers as much as possible


In First Grade the students begin typing with Mavis Beacon Teaches Typing 15 (the one and only piece of Windows only software I will miss in the transition to Edubuntu in the lab. If anyone has any recommendations for a similar full-featured typing tutor that will work with GNU/Linux I'd love to hear about it). They also start doing somewhat harder online activities since they can read fairly well by this age.


In Second Grade we introduce Open Office Writer. I thought it was a bit early to start with word processing so young, but the Massachusetts state technology standards called for it so I thought we'd give it a shot. After just a year of typing the kids aren't all that adept at using the program, but I've noticed that it serves as a good introduction to the common interface of toolbars and drop down menus. It also introduces the ideas of saving, opening, and printing.


In Third Grade we introduce Open Office Impress. This is actually the program I would have started with in second grade because it is so visual, but third grade seems to be about the youngest age a student can really begin doing coherent presentations in front of the class so I suppose it works here as well. Of course we continue building on what the students have learned in previous years so they learn more about Writer this year as well.


In Fourth Grade the students begin learning Scribus. Publishing and writing labs are a big part of our school's fourth grade curriculum so this was an obvious choice.

Fifth grade focuses on Kompozer and web design in preparation for middle school and the online portfolios that the students begin in 6th grade.


Sixth grade centers around Web 2.0 sites and strategies like blogger and google docs and posting to forums and emailing experts. I originally wanted to do this in 5th grade but didn't feel comfortable asking elementary school students to sign up for the Internet IDs they will need to access certain sites.


In Seventh Grade the students learn Inkscape in the hopes that it will help them spice up their digital portfolios.

In Eighth Grade the students learn GIMP for the same reason as Inkscape.

Basically the idea is to give students the hard skills they need to be able to satisfy their class requirements in the method they prefer. If they want to fulfill an assignment on the fall of the Roman empire they can choose to write a paper, create a brochure, make a newspaper or magazine, create a website, present a powerpoint or whatever. You asked if the curriculum meets the needs of teachers and I feel like this is where it helps them out (Internet safety and research skills and stuff like that falls in the librarians domain) although I will be asking the teachers to fill out a survey on the whole curriculum at the end of the year so I guess I'll know more after that happens. I also like the idea of introducing students to computer parts and programming at least a little bit, thus the mention of kturtle which I'm hoping to introduce across every grade 2 and up (as soon as I learn Logo a little better).


As much as I'd like some new iMacs and to be able to work with the middle schoolers on video editing and animation I'm also pretty committed to using open source (or at least free) software not only to avoid legacy costs for the school but also so that anything I teach in the lab can be practiced at home by the students for no additional cost (assuming the student has a computer at home). I'm more likely to just hope for some new P4s to come through the school, buy some RAM for them and set up some stand-alone Edubuntu boxes.


Sorry for the long winded response, I wasn't sure where you were coming from and (as with all teachers) once I get started I can be hard to stop. Are you in education as well? If you're in the area I'll be presenting on my Edubuntu experiences at the SCALE conference in Los Angeles next month as well as at the CUE conference in Palm Springs in March. If you're interested you can learn more about my school at
aeacs.org and see my presentation at hartmanbot.com. Cheers! -joe




Hi Joe,

Would you mind commenting a bit about how you are using the software

above at different grade levels? *Do the programs you mention meet the
educational needs of the kids and teachers?

Is there software you miss from your old setup (I assume Windows since
you mention viruses).



> I was hoping to use Kino and Blender with the middle schoolers at some point
> in the future, but it isn't a big deal to postpone those plans if need be.

I'd hope that the savings from using ltsp would help buy a few nice

machines for video editing. *Seems like a few nice iMacs would be a
nice addition.


--
Bill Moseley
moseley@hank.org





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nigel barker 01-11-2008 01:10 PM

Advice on getting a computer lab server
 
Hi Joe,

I am using Debian Edu (and a few Edubuntu workstations) in an IB PYP and
Diploma school. (We were an MYP candidate, but decided not to pursue
that after all.) I was wondering if you know of any other IB schools
using LTSP or other free software? I have searched a bit over the years,
but only discovered a couple of schools that no longer use it. Is it
just me and you, or are there others? How can we share ideas regarding
the PoI, etc? Can we get our kids to work together on some units? Do you
have to deal with FUD?
I was the one who asked the IB to publish the new PYP planner in ODF
format. (though I have a better version if you want it). Can we team up
and make them do more to address open standards?

cheers
(lets go off list, but I hope the list didn't mind me posting this in
case other IB schools are listening)
nigel

Joseph Hartman wrote:
> Hi Bill,
>
> The current curriculum has just undergone some recent changes in light
> of my beginning to teach middle school students in addition to
> elementary school students for the first time but I'd be happy to
> comment about the reasoning behind the current plan.
>
> It arose out of specific school needs, state and professional
> organization standards (especially ISTE and Massachusettes since
> California doesn't have specific computer related technology
> standards), and my own experience/vision. The primary driving force
> towards Linux, LTSP, and Edubuntu arose out of necessity as much as
> anything else. I work at a charter school and we inherited a campus
> from a defunct public school complete with network and computers, the
> vast majority of the latter being from the wrong side of the
> millennium. Many of the machines we are using now were donated by
> organizations (the border patrol, district attorney's office, private
> companies, German Consulate) that were upgrading infrastructure and
> would otherwise have been discarded. Thus the ability to use these
> many underpowered and outdated machines as thin clients appealed to
> me. I'd guess we have about 200 workstations on campus altogether, of
> which about 50 are Pentium 4 and four are Core 2 Duo (the
> administrators' laptops and my own). The rest are P3, P2, or slower.
>
> I should also mention that my school is an International Baccalaureate
> (IB) World School on the elementary side while the Middle School that
> just started up last year is in the accreditation process.
> Additionally, the elementary school operates under a German Immersion
> program that has the students spend one week learning in English under
> an English speaking teacher and the next week learning in German under
> a German speaking teacher. And the campus we inherited two years ago
> resides in a primarily Spanish-speaking and relatively underprivileged
> area of San Diego so our incoming students are rapidly changing the
> face of the school. All additional reasons to use the similarly
> multicultural and globally minded products of Ubuntu and GNU/Linux.
>
> Because we are an IB school on the elementary side we have what is
> called a Program of Inquiry (POI) that is essentially a matrix of 6
> big ideas per grade (so 36 big ideas total) that are divided up and
> taught throughout the year in addition (and hopefully in conjunction
> with) the normal classroom curriculum. POI topics are things like
> "objects in the sky move in predictable patterns" or "water is
> essential to life" and typically last for about 6 weeks. Thus my own
> curriculum assignments are designed around supporting these topics
> while at the same time teaching the students specific hard skills
> about the programs they are learning to use. I also try to collaborate
> with the teachers and their own projects as much as possible, although
> this is difficult since I only see each class for 45 minutes per week.
>
> On to the curriculum....
>
> In Kindergarten the students learn how to use a computer as many have
> never used one before or if they have it was for very specific tasks.
> Mouse practice, Tuxpaint, and learning about the parts of a computer
> pretty much sum it up, although I do try to collaborate with the
> teachers as much as possible
>
> In First Grade the students begin typing with Mavis Beacon Teaches
> Typing 15 (the one and only piece of Windows only software I will miss
> in the transition to Edubuntu in the lab. If anyone has any
> recommendations for a similar full-featured typing tutor that will
> work with GNU/Linux I'd love to hear about it). They also start doing
> somewhat harder online activities since they can read fairly well by
> this age.
>
> In Second Grade we introduce Open Office Writer. I thought it was a
> bit early to start with word processing so young, but the
> Massachusetts state technology standards called for it so I thought
> we'd give it a shot. After just a year of typing the kids aren't all
> that adept at using the program, but I've noticed that it serves as a
> good introduction to the common interface of toolbars and drop down
> menus. It also introduces the ideas of saving, opening, and printing.
>
> In Third Grade we introduce Open Office Impress. This is actually the
> program I would have started with in second grade because it is so
> visual, but third grade seems to be about the youngest age a student
> can really begin doing coherent presentations in front of the class so
> I suppose it works here as well. Of course we continue building on
> what the students have learned in previous years so they learn more
> about Writer this year as well.
>
> In Fourth Grade the students begin learning Scribus. Publishing and
> writing labs are a big part of our school's fourth grade curriculum so
> this was an obvious choice.
>
> Fifth grade focuses on Kompozer and web design in preparation for
> middle school and the online portfolios that the students begin in 6th
> grade.
>
> Sixth grade centers around Web 2.0 sites and strategies like blogger
> and google docs and posting to forums and emailing experts. I
> originally wanted to do this in 5th grade but didn't feel comfortable
> asking elementary school students to sign up for the Internet IDs they
> will need to access certain sites.
>
> In Seventh Grade the students learn Inkscape in the hopes that it will
> help them spice up their digital portfolios.
>
> In Eighth Grade the students learn GIMP for the same reason as Inkscape.
>
> Basically the idea is to give students the hard skills they need to be
> able to satisfy their class requirements in the method they prefer. If
> they want to fulfill an assignment on the fall of the Roman empire
> they can choose to write a paper, create a brochure, make a newspaper
> or magazine, create a website, present a powerpoint or whatever. You
> asked if the curriculum meets the needs of teachers and I feel like
> this is where it helps them out (Internet safety and research skills
> and stuff like that falls in the librarians domain) although I will be
> asking the teachers to fill out a survey on the whole curriculum at
> the end of the year so I guess I'll know more after that happens. I
> also like the idea of introducing students to computer parts and
> programming at least a little bit, thus the mention of kturtle which
> I'm hoping to introduce across every grade 2 and up (as soon as I
> learn Logo a little better).
>
> As much as I'd like some new iMacs and to be able to work with the
> middle schoolers on video editing and animation I'm also pretty
> committed to using open source (or at least free) software not only to
> avoid legacy costs for the school but also so that anything I teach in
> the lab can be practiced at home by the students for no additional
> cost (assuming the student has a computer at home). I'm more likely to
> just hope for some new P4s to come through the school, buy some RAM
> for them and set up some stand-alone Edubuntu boxes.
>
> Sorry for the long winded response, I wasn't sure where you were
> coming from and (as with all teachers) once I get started I can be
> hard to stop. Are you in education as well? If you're in the area I'll
> be presenting on my Edubuntu experiences at the SCALE conference in
> Los Angeles next month as well as at the CUE conference in Palm
> Springs in March. If you're interested you can learn more about my
> school at aeacs.org <http://aeacs.org> and see my presentation at
> hartmanbot.com <http://hartmanbot.com>. Cheers! -joe
>
>
>
> Hi Joe,
>
> Would you mind commenting a bit about how you are using the software
> above at different grade levels? Do the programs you mention meet the
> educational needs of the kids and teachers?
>
> Is there software you miss from your old setup (I assume Windows since
> you mention viruses).
>
>
> > I was hoping to use Kino and Blender with the middle schoolers
> at some point
> > in the future, but it isn't a big deal to postpone those plans
> if need be.
>
> I'd hope that the savings from using ltsp would help buy a few nice
> machines for video editing. Seems like a few nice iMacs would be a
> nice addition.
>
>
> --
> Bill Moseley
> moseley@hank.org <mailto:moseley@hank.org>
>
>


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Gavin McCullagh 01-11-2008 01:39 PM

Advice on getting a computer lab server
 
Hi,

On Thu, 10 Jan 2008, Joseph Hartman wrote:

> I actually started rolling out an edubuntu lab earlier this year and it
> became painfully clear early on that the server I have (3.0 GHz P4 Dell
> with 4GB Dual Channel DDR RAM) was not going to be adequate to handle all
> the thin clients.

How many was that? I had understood from documentation that you should be
able to get up to 25-30 with that.

> I have since dedicated my efforts towards setting up MiniLANs in each
> teacher's classroom with the P4 servers handling just 3 to 6 thin
> clients. This seems to be working alright, although things are still
> pretty slow.

Another thing to consider is the disks. IDE disks and controllers are
pretty poor for multiple user access. If you're going to have many users,
SCSI is generally the way forward. 3-6 should probably be okay with IDE I
would have thought and with a Pentium 4 running openoffice/firefox. You
should perhaps try to check if the problem is lack of memory or cpu on the
server. Highly animated applications like tuxtype, tuxmath, et al,
gcompris, video will cause video slowdowns which could be your problem.

> I was hoping to use Kino and Blender with the middle schoolers at some point
> in the future, but it isn't a big deal to postpone those plans if need be.

Intensive video stuff sounds like something which might not work well.

> In my current lab if I try to run more than about 7 thin clients they freeze
> up just playing flash games or running tuxtyping.

These applications could indicate network bandwidth troubles, particularly
if they all share, say a cheap 100Mbit hub.

There have also been reports of tuxtype and tuxmath crashing thin clients
so perhaps that problem is affecting you (one which might not go away with
bigger hardware). Seemingly turning sound off on the client can remedy
this issue (I'm not saying that's the answer, but it might help you
identify the problem).

> Like I said, I have 4GB of Dual Channel DDR RAM so is the bottleneck with
> my 10/100 switch or my P4 CPU? Until now I've thought it was the CPU
> because when I look at the system monitor the CPU maxes out pretty quick.
> (maybe I should bring my c2d in from home and try it out to see how it
> holds up)

I'm afraid it's hard to pinpoint from here. You need to look at ways to
measure RAM used (the output of the "free" command is a start) and cpu load
("uptime" and "top"). If you have some way to measure network load that
would also be interesting to see.

Munin is a very useful thing for monitoring usage of bandwidth, disk, cpu
load, ram usage, etc.

http://www.debian-administration.org/articles/229
http://www.howtoforge.com/server_monitoring_monit_munin

> If I want to use the above programs and keep my current curriculum will a
> single server with 2 dual core xeons and 8 GB RAM be fast or just
> adequate? I want the lab to be fast. (obviously I'm just asking your
> opinion here)

If the lab is 30-35 users I would hope so but our usage tends to be more
sporadic so I don't have enough experience to be sure. A couple of other
large installs (Jim K has 70 thin clients?) have used several bonded
Gigabit interfaces in order to give the server >1Gb/sec access to the
network.

> Finally, what kind of switch should I get? Should I go all gigabit or is it
> enough to just be gigabit to the server and 10/100 to the clients? I do a
> lot of flash based reading games and stuff with the lower grades like
> starfall.com and so I absolutely must have these activities perform well.

The server really should have at least one gigabit interface. Limiting
each client to 100Mb/s is perhaps not a bad thing as it stops a rogue
client from saturating the server's network card and in principal leaves
the other 900Mb/s for other clients.

Gavin


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"Kemp, Levi" 01-11-2008 02:34 PM

Advice on getting a computer lab server
 
> -----Original Message-----
> From: edubuntu-users-bounces@lists.ubuntu.com
> [mailto:edubuntu-users-bounces@lists.ubuntu.com] On Behalf Of
> Gavin McCullagh
> Sent: Friday, January 11, 2008 8:40 AM
> To: edubuntu-users@lists.ubuntu.com
> Subject: Re: Advice on getting a computer lab server
>
> Hi,
>
> On Thu, 10 Jan 2008, Joseph Hartman wrote:
>
> > I actually started rolling out an edubuntu lab earlier this
> year and
> > it became painfully clear early on that the server I have
> (3.0 GHz P4
> > Dell with 4GB Dual Channel DDR RAM) was not going to be adequate to
> > handle all the thin clients.
>
> How many was that? I had understood from documentation that
> you should be able to get up to 25-30 with that.
>
> > I have since dedicated my efforts towards setting up
> MiniLANs in each
> > teacher's classroom with the P4 servers handling just 3 to 6 thin
> > clients. This seems to be working alright, although things
> are still
> > pretty slow.
>
> Another thing to consider is the disks. IDE disks and
> controllers are pretty poor for multiple user access. If
> you're going to have many users, SCSI is generally the way
> forward. 3-6 should probably be okay with IDE I would have
> thought and with a Pentium 4 running openoffice/firefox. You
> should perhaps try to check if the problem is lack of memory
> or cpu on the server. Highly animated applications like
> tuxtype, tuxmath, et al, gcompris, video will cause video
> slowdowns which could be your problem.
>

I've heard of a few people getting away with SATA as a cheaper
alternative to SCSI. It will perform better than IDE, but it's still
going to be no where near as good as a SCSI setup.

> > I was hoping to use Kino and Blender with the middle
> schoolers at some
> > point in the future, but it isn't a big deal to postpone
> those plans if need be.
>
> Intensive video stuff sounds like something which might not work well.
>
> > In my current lab if I try to run more than about 7 thin
> clients they
> > freeze up just playing flash games or running tuxtyping.
>
> These applications could indicate network bandwidth troubles,
> particularly if they all share, say a cheap 100Mbit hub.
>

I would have to concur. I don't think a 100Mbit connection to the server
is adequate, because you'd have to think that each of you clients would
only have 10Mbits to use. I'd suggest getting a cheap gigabit card for a
server to try but coming up with a switch with gigabit would prove more
difficult.

> There have also been reports of tuxtype and tuxmath crashing
> thin clients so perhaps that problem is affecting you (one
> which might not go away with bigger hardware). Seemingly
> turning sound off on the client can remedy this issue (I'm
> not saying that's the answer, but it might help you identify
> the problem).
>
> > Like I said, I have 4GB of Dual Channel DDR RAM so is the
> bottleneck
> > with my 10/100 switch or my P4 CPU? Until now I've thought
> it was the
> > CPU because when I look at the system monitor the CPU maxes
> out pretty quick.
> > (maybe I should bring my c2d in from home and try it out to
> see how it
> > holds up)
>
> I'm afraid it's hard to pinpoint from here. You need to look
> at ways to measure RAM used (the output of the "free" command
> is a start) and cpu load ("uptime" and "top"). If you have
> some way to measure network load that would also be
> interesting to see.
>
> Munin is a very useful thing for monitoring usage of
> bandwidth, disk, cpu load, ram usage, etc.
>
> http://www.debian-administration.org/articles/229
> http://www.howtoforge.com/server_monitoring_monit_munin
>
> > If I want to use the above programs and keep my current curriculum
> > will a single server with 2 dual core xeons and 8 GB RAM be fast or
> > just adequate? I want the lab to be fast. (obviously I'm
> just asking
> > your opinion here)
>
> If the lab is 30-35 users I would hope so but our usage tends
> to be more sporadic so I don't have enough experience to be
> sure. A couple of other large installs (Jim K has 70 thin
> clients?) have used several bonded Gigabit interfaces in
> order to give the server >1Gb/sec access to the network.
>

Our lab functions well with 2 xeons and 3.2gig of ram (32bit) and we
have had 30 students at once on firefox w/ flash, openoffice, and
whatever games they can find under he edutainment. They can even all use
reading counts running on flash. We don't do any heavy video graphics
stuff like blender so I can't say there.

> > Finally, what kind of switch should I get? Should I go all
> gigabit or
> > is it enough to just be gigabit to the server and 10/100 to the
> > clients? I do a lot of flash based reading games and stuff with the
> > lower grades like starfall.com and so I absolutely must
> have these activities perform well.
>
> The server really should have at least one gigabit interface.
> Limiting each client to 100Mb/s is perhaps not a bad thing
> as it stops a rogue client from saturating the server's
> network card and in principal leaves the other 900Mb/s for
> other clients.
>
> Gavin
>
>
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> edubuntu-users@lists.ubuntu.com
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"David Trask" 01-12-2008 05:24 PM

Advice on getting a computer lab server
 
Ian,

A faster server will definitely help, but the first problem is the 10/100
switch and perhaps the NIC coming from the server. Back in the old days,
(I've been running linux terminals in my school since 2001) I used to have
this issue....with Tuxtyping and so forth. One day I tried an
experiment...I switched to gigabit. I already had a gigabit NIC in the
server, but it was connected to a 100 baseT port. I simply got a switch
with a gigabit uplink port and WOW! Suddenly, everyone could play
Tuxtyping!

It's like this. Imagine you have 20 kids in a room. When the bell rings
they are going to exit the room and go out into the hall and then each go
into 20 different classrooms individually. They will exit via a normal
size door and enter the other classrooms by normal sized doors. The issue
becomes, in this case, how quickly they can exit the first room.
NOW...take the same scenario except in the originating room...now you have
a large door the size of a garage or barn door. Same kids....same
destination...except now they can leave the originating room MUCH faster.
This is the analogy of what is happening at the server. The bottleneck
right now is at the server...by switching to gigabit coming out of the
server (gigabit NIC and gigabit switch) you now shift the bottleneck down
to the client...where it belongs.

I hope this helps! I too run Starfall reading and a host of other
Flash-based sites in my lab. We are able to do so without any issues :-)

Ian Mackenzie <ianmackenz@gmail.com> writes:
>Joe wrote:
>
>Here's a few final questions if you don't mind.
>
>In my current lab if I try to run more than about 7 thin clients they
>freeze up just playing flash games or running tuxtyping. Like I said, I
>have 4GB of Dual Channel DDR RAM so is the bottleneck with my 10/100
>switch or my P4 CPU? Until now I've thought it was the CPU because when I
>look at the system monitor the CPU maxes out pretty quick. (maybe I
>should bring my c2d in from home and try it out to see how it holds up)
>
>If I want to use the above programs and keep my current curriculum will a
>single server with 2 dual core xeons and 8 GB RAM be fast or just
>adequate? I want the lab to be fast. (obviously I'm just asking your
>opinion here)
>
>Finally, what kind of switch should I get? Should I go all gigabit or is
>it enough to just be gigabit to the server and 10/100 to the clients? I
>do a lot of flash based reading games and stuff with the lower grades
>like [ http://starfall.com ]starfall.com and so I absolutely must have
>these activities perform well.
>
>--------------
>
>
>
>(From the Edubuntu web site) ?If you have more than 10 users, it is
>recommended to use gigabit ethernet for your LTSP servers. Although
>normal usage ranges from 0.5 to 2mbit, clients can peak quite high
>(70mbit), especially when watching multimedia content. ?
>
>
>
>So, gigabit from server -> switch and 100M from switch to client PCs
>sounds about right. I"m about to build a core2Quad to serve the computer
>lab, and see how it runs, and if there is room for expansion.
>
>Ian Mackenzie
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David N. Trask
Technology Teacher/Director
Vassalboro Community School
dtrask@vcsvikings.org
(207)923-3100



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