A Computer Lab with No Windows, Part I

An application of Linux Terminal Server in Manitoba's largest high school.
Choice of Hardware

Two years ago, I started my Linux terminal server project with an Athlon 1.2GHz CPU, 1.5GB of DDR RAM and an IDE 40GB hard drive as the server and a variety of older Pentium-grade PCs (ranging from 133MHz to 350MHz CPUs and having 32MB or more RAM) as workstations. To guarantee better network throughput, I bought three 100Mbps 24-port switches, consumer grade, for about $120 each. The system ran fine for up to 15 workstations, but it started running out of resources (I used the top command to monitor) when more workstations were added. As some of the courses have a class sizes of up to 30 students, I had to build a more powerful server to run this Linux terminal server network.

In September 2003, AMD's Opteron 24x series was available at a price comparable to the Xeon's 2.x from Intel. It was a difficult decision to choose between Xeon or Opteron. The Opteron is a 64-bit CPU but it could be purchased at about the same price as a 32-bit Xeon. Plus, it looks especially attractive when future 64-bit upgrades are considered. However, the only distribution with 64-bit support was SuSE, and most other applications, such as OpenOffice.org, still were running on 32-bit. I finally chose Xeon as I found it beats Opteron in most 32-bit tests, and the hyperthreading technology made my dual Xeon system functions like a system with four CPUs.

Having made those decision, below are the specifications of my new Linux terminal server, built in September 2003:

  • Intel SE7501BR2 Dual Xeon motherboard with on-board Ultra320 SCSI

  • 2 Xeon 2.4 GHz CPUs

  • 4GB of DDR RAM with ECC (Error Correction Code)

  • 2 36GB Seagate Ultra320 hard drives

With a special power supply and a server case, the whole server cost $4,500 including tax. By the time you read this article, it certainly would be cheaper and have better, faster and more powerful components.

The Manitoba chapter of Computers for School has been a huge supporter of my Linux terminal project. I received about 36 IBM 300PL slim-line PCs as workstations and a 100Mbps Intel 510P 24 Port switch from them for free. The I300PLs have built-in video and built-in sound as well as built-in Intel 100Mbps network cards. While they do not have enough power to run MS Windows (that, in fact, that was the main reason I was able to get as many as I wanted from Computer for Schools--no other school wanted them), they are perfect as a standard workstation in my classroom. The built-in network card supports PXE booting; some of the older BIOSes needed an upgrade, but that's downloadable from the IBM support site. On top of each on-board Pentium 200MHz CPU is a big heat sink with no cooling fan. Again, this is another advantage as no cooling fans need to be replaced.

My rule of thumb for memory is 100MB for each station. However, ECC RAM works in pairs, and I had no choice but to get the maximum amount of 4GB, the maximum RAM size any 32-bit system can handle. Thus, for people who want to build a LTSP to support more than 30 workstations, 32-bit CPUs are out of the question-- 64-bit CPUs, such as Opteron, should be considered. With the 64-bit support coming in future Linux distribution releases, Opteron definitely will my choice for my next terminal server.

Although the SCSI drives are more expensive (more than double the price of IDE), they deliver excellent performance on my network. With the new server, all the workstations (26 at present) can run KDE, OpenOffice.org, Web browsers and other applications smoothly and seamlessly. Recently, I installed several systems with serial ATA hard drives and found they perform much better than those with Ultra-DMA IDE drives. With the price of serial ATA drives coming down so rapidly (they are almost the same price as the parallel IDE drive), they probably soon will make SCSI obsolete--SCSI is just too expensive.

With a standard configuration of only 32MB of RAM, built-in 2MB S3 video, built-in sound and no hard drive, the workstations performance is comparable to a PC with 2GHz and 256MB of RAM running MS Windows. After typing in the user id and password, a beautiful KDE (or GNOME) window manager can be loaded in less than 10 seconds.

Burn Your Own Copy of LTSP CD

As far as getting software for the Linux terminal server, there are several choices. The easiest way is to download it from K-12 Linux Project site. Most of the mirror sites are educational, and they all are connected to the fastest Internet backbone. I usually can get up to 1Mbps on the ADSL link from my high school (during school hours when many students also are using the ADSL link) and can download the iso image of three CDs in less than two hours. Once the iso images are downloaded, check the download with the md5sum error and then burn your own CD with a standard CD burner. If you don't have access to a high-speed link, you can purchase the CD from the K-12 Linux Project site or from any Linux CD Web site; the cost is a few dollars plus shipping, the shipping cost is usually higher than the CD cost.

If you have your own Linux distribution CDs, you can download only the terminal server components from the Linux Terminal Server Project site. This is the general Linux Terminal Server Project, without the K12 chapter.

The main catch in getting the software is the driver for your mass storage, the hard drive. Unless you need to support only a small number of workstations--say, 5 or less--a SCSI or SATA interface is essential for good performance. Unlike the parallel IDE, neither the SCSI nor the SATA is a standard interface, and a special driver for Linux is needed. Moreover, the driver needed is for the SCSI or SATA interface and, in general, should be supplied by the motherboard maker or the interface maker. The SCSI driver I got from Intel was written for Red Hat 8.0, and as a result, I can choose only the LTSP software that was built on Red Hat 8.0. In fact, the driver from Intel didn't work with Red Hat 9.0, so I had to settle for LTSP 3.0, which was built on Red Hat 8.0.

______________________

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Re: A Computer Lab with No Windows, Part I

Anonymous's picture

It's fine to meet same people interest in an altruistic mision ..... why don't you try:

Thinstation.sf.net

all pre-processed ....No need to install compile....etc an best of all

a la carte prebuilt iso images ......

Ask 4 more .... pxes.sf.net .... looks alike

Karlitros

Re: A Computer Lab with No Windows, Part I

Anonymous's picture

Congratulations both on your linux project and a superbly written article! Excellent work! I have also been running a linux lab at Monarch Park Collegiate in Toronto for the past two years.

Statistics for comparison with other computer systems/operating systems/proprietary software: ;-)

For the past two years, our 20 station lab, used for computer science and computer engineering courses has the following record, (started with Mandrake 9.2, recently upgraded to Mandrake 10.0):

Reimaging: 0 (zero)
Viruses, worms, trojans, etc.: 0 (zero)
Lost student/teacher files, etc.: 0 (zero)
Software cost: 0 (zero)
Electricity used between 5 pm and 8 am: 0 (zero)
(I add this for comparison with a rather ludicrous system of
overnight reimaging being done in some schools, etc. for a certain well known proprietary system ;-))
Serial numbers, CDkeys, secret passwords, secret decoder rings, etc.: 0 (zero)
Downtime in minutes: 0(zero)
Copies of all software for staff, students, teachers, parents, taxpayers, etc.for use at home, school, work, university, business, etc.: unlimited

If you would like further details, feel free to contact:
edmontgomery@hotmail.com

Re: A Computer Lab with No Windows, Part I

Anonymous's picture

Hello,

What the article talks about is, having a high powerful server for setting up LTSP clients.

Ours is a linux technology solutions company located in Chennai, INDIA providing
LTSP based thinclient solutions for the academic institutions in Tamilnadu.

Recently, we have implemented a complete thinclient network for a University Study Centre (Bharath
Post Graduate College, Mylapore) in Chennai with the following setup and running successfully without
any Network/System Administrators and with impressive performance and we would like to
share our great experience with the readers.

We have setup a 70-seat computer lab with an LTSP server and also second Windows-2000 Server
running terminal services which is accessed through rdesktop from LTSP Clients.

The LTSP server configuration is

Intel Original Desktop Motherboard (see, no Server Motherboard or Dual processor)
Pentium-IV 3.0 GHz with HyperThreading
1 GB DDR RAM
1 Adaptec UW SCSI Adapter
7200 RPM Seagate SCSI Hard disk
100 Mbps Realtek-8139 Network card

The Windows-2000 server configuration is

VIA Chipset Desktop Motherboard
Pentium-IV 2.6 GHz
1 GB DDR RAM
1 Adaptec UW SCSI Adapter
10K RPM IBM SCSI Hard disk
100 Mbps Realtek-8139 Network card

The client PCs were normally Cyrix 200 Mhz, Pentium-100, 133, 166 with 32MB RAM and 100 Mbps
network card and with 1 MB PCI VGA Card.

The initial OS loading time is approximately about 15 seconds. After logging in,
the KDE/GNOME Desktop loads in less than 5 seconds.

The applications like OpenOffice, Qt, KDevelop loads in less than 5 seconds in all
the thin clients concurrently.

Presently, the entire study centre network is completely thinclients and there is no
single workstation. The Study Centre Management has complete satisfaction with this
kind of setup and planned to increase 100 more clients having the same kind of above setup.

Our Address:

LinuXpert Systems, Chennai.
Tamilnadu, INDIA.
E-mail: linuxpert@vsnl.net

ThinClients without Linux SERVER

Rehan Shaikh's picture

why do you require linux server,

it can be done without linux servers also, there are many products available in the market like Enjay Thinclients from Enjay network Solutions
www.enjayworld.com

Rehan. . . . .

Re: A Computer Lab with No Windows, Part I

Anonymous's picture

Thanks for the sharing your experiences, perhaps I can save on SMP which the new LTSP isn't stable on yet and just get a P4, use the extra cash for scsi hd's and RAM for my lab.

Re: A Computer Lab with No Windows, Part I

Anonymous's picture

Good article, and I am glad to see LTSP being used more and more in educational settings, however there are some significant errors regarding the hardware information.
Those interested in this information, please look at:
This StorageReview post.
An addendum to the post is that using >4GB of RAM would work fine on a Xeon system. While a single process can only use 4GB of RAM, up to 64GB of RAM can be addressed in 4-GB blocks by multiple processes. Because LTSP servers deal with manyh processes, this 4GB/process limitation would not be a major hurdle.

Additionally, while the specific benchmarks run by the administrator may have performed better on the Xeon, the Opteron is well known for being significantly faster in most 32-bit tasks, particularly in environments with many demanding processes.
The fact that OpenOffice is only available as a 32-bit application is not significant, because 64-bit Linux can run 32-bit applications at native speed, just without the use of the extra registers or >4GB of memory per process.

Re: A Computer Lab with No Windows, Part I

Anonymous's picture

I enjoyed your article and I want to say well done!
As a newbie in Linux, I am very anxious to know( in detail) how to set up the server and the clients.

This type of project will be of immense benefit to some of us in this part of the world(Nigeria), where a lot of PCs are just thrown out, because they can't run Windows fast enough. These PCs can be re used.

I am looking forward anxiously to the next part of your interesting article.

Regards,

Maurice Poor.

Re: A Computer Lab with No Windows, Part I

Anonymous's picture

I teach high school C++ in BC, Canada. I am a FOSS Free Open Source Software advocate. I would love to try this with my lab. I run linux at home so I am not a newbie. But I don't have experience as a linux admin. We are still using Windows NT with 233Mhz PII's. I think this would be an excellent idea for the lab. Just curious if a server would handle all the kids trying to compile something at the same time? I think articles like this are fantastic!!! I have emailed it around the district. I think this is the future of K-12 education.

Re: A Computer Lab with No Windows, Part I

Anonymous's picture

This poster started 8 of 11 sentences with the word "I", and a 9th with "But I".

Take a year off and go back to 9th grade....

Bleh. Take a year off and lea

Anonymous's picture

Bleh. Take a year off and learn to be less pedantic.

The Network is the Computer

Anonymous's picture

I set one of these up for a local housing agency and It worked very well even with a desktop masquerading as a server. (1.7ghz Compaq 512MB 40GB) The one thing that I advise anyone setting one of these up to do is to invest in your network. You will want at least a 100mb switch and 100mb cards in each of your machines. You may even want to put multiple NICs in your server to give it more bandwith. As people file into your lab and log onto websites to start playing games, your network will become a bottleneck very quickly. Otherwise, this is a great solution to problems inherent in standalone PCs. i.e. short life cycle, decentralization, and HD failures. Plus you will discover a lot of cool things that Linux allows you to do out of the box that are either impossible or painful to do in Windows.

Practice with one thin client and one server. Once you get that one working, the rest are cake. Good luck to all.

Re: A Computer Lab with No Windows, Part I

Anonymous's picture

Wonderful article, I am pleased to read of a teacher who is teaching students how to use computers rather then teaching them how to use Wintel machines. With education budgets stretched to the max the last thing schools need to do is purchase expensive Wintel boxes or Macintoshes. While these computers do serve good purposes much of what students need can be accomplished for much less money and work a whole let better. Thank you for proving that there can be viable alternatives for schools.

Re: LTSP combined with OpenMosix?

Anonymous's picture

Something that occurred to me that might or might not work well, is that it would probably be trivial to boost server power if you used OpenMosix (openmosix.sourceforge.net) kernels.

OpenMosix is a simple cluster solution that autodetects new computers on the network running OpenMosix, and automatically starts sharing CPU power and memory.

It might even be possible to have all the thin clients be part of the cluster.

To play a bit with OpenMosix, download ClusterKnoppix (http://bofh.be/clusterknoppix/) and try it on a few computers. Those of you with LTSP expertise might know if it's feasible to combine usage of these technologies.

Re: A Computer Lab with No Windows, Part I

ghbpiper's picture

I have been wanting to do this for some time now. The main obstacle(s) are naturally certain 3rd party, proprietary applications that teachers cannot or will not live without. 2 are products from renaissance software (Accelerated Reader and STAR Reading), and the other is a MS Access-based student information system.

Taking any of these away would produce hoardes of angry users bearing torches and pitchforks at the door to my office :( Any thoughts? (Crossover office, WINE, ???)

Re: A Computer Lab with No Windows, Part I

Anonymous's picture

keep the licensing you have an use tightvnc to access the ms computers. If you have to keep 5 MS machines with VNC you can still access them from ANY thin client machine. You also keep them centrally located and it changes nothing from what you have now other than they have thin clients to use programs from and can use the MS programs on an as-needed basis.

Re: A Computer Lab with No Windows, Part I

Anonymous's picture

Just use thin client Linux on the clients and connect to both Unix and MS Windows servers, depending on the situation.

Thinstation (thinstation.sourceforge.net) is an excellent example of such a clients OS (I'm involved in this project myself :-)

Of course you'll have to pay for client access license to the MS Windows box, but you still save a lot on hardware and administration.

Re: A Computer Lab with No Windows, Part I

ghbpiper's picture

Yeah, I know, but that's (MSTS) part of what I'm trying to avoid, although it may be a pipe dream at the moment.

checkout http://www.lumensoftware.com - Looks like they've packaged something like ltsp (or maybe ltsp itself) plus some winderz-compatibility stuff, all designed to work with thin clients.

IBM 300PL More Expensive Than Microtel SYSMAR587 PC

Anonymous's picture

Microtel SYSMAR587 PC With AMD Duron 1.4 GHz
$158.98
http://www.walmart.com/catalog/product.gsp?product_id=2416619&cat=86798&...

IBM 300PL
$159.00
http://www.compgeeks.com/details.asp?invtid=300PL667-3B

If you're not getting your client hardware for free, it seems a
waste not to get a very inexpensive new PC.

I've also been trying to compare LTSP to new PCs running Knoppix which has many advantages over LTSP:

o Client performance should be better
o The clients work even if the server reboots
o Certain applications (e.g. TuxRacer) can realistically only be run on a local PC.
o PCs can be individually upgraded, and some PCs or people
could have customized CDs for certain applications (e.g. Kindergarten class could have one set of apps, while the C++ class could have another)

Disadvantages:

o Have to make and distribute CDs, also for updates
o Have to deal with rogue CD makers.

Re: IBM 300PL More Expensive Than Microtel SYSMAR587 PC

Anonymous's picture

by the way the attrition rate on those very inexpensive new pcs will make you wish you bought more expensive pcs, either new or used.

Re: IBM 300PL More Expensive Than Microtel SYSMAR587 PC

Anonymous's picture

>>by the way the attrition rate on those very inexpensive new pcs will make you wish you bought more expensive pcs, either new or used.

It seems you have missed the point. In a terminal server envirment the attrition rate is extremely low versus the networked PC model. Plus in a termianl server envirment with the correct NICs you can remove your CD-ROM, Hard-drive, Floppy-Drive, and almost all moving parts from the computer once you do that the only part that will usually fail is the power supply.

He can probably use those same terminals for 3-6 years without having to upgrade.

Re: IBM 300PL More Expensive Than Microtel SYSMAR587 PC

Anonymous's picture

If you pay more than 50 bucks for the thinclient box you're ripping yourself off.
p166 is overkill. you don't need to buy them with hddisks, cdroms, zips, etc.
find places that sell just the stripped PC. They do exist. Last year I saw a lot of Dell pentium 100s for 19 dollars each. they would have been perfect if i hadn't already all the desktops i need.

Hardware Requirements

Anonymous's picture

Why did you need to resort to such a powerful server?

I have been running a 25-seat computer lab with an LTSP server that is very slim by comparison.

2 700 Mhz Pentium III CPUs
512 MB RAM
2 40 GB HDs

The thin stations are very similar to yours. This is running Mandrake 9.1 + LTSP. It works great, even for the heavier apps such as openoffice.org 1.0

I would love to hear the experience of other folks in terms of hardware requirements.

Re: Hardware Requirements

Anonymous's picture

Something that occurred to me that might or might not work well, is that it would probably be trivial to boost server power if you used OpenMosix (openmosix.sourceforge.net) kernels.

OpenMosix is a simple cluster solution that autodetects new computers on the network running OpenMosix, and automatically starts sharing CPU power and memory.

It might even be possible to have all the thin clients be part of the cluster.

Re: Hardware Requirements

Anonymous's picture

"It might even be possible to have all the thin clients be part of the cluster."

That would be really interesting because many "old" computers have still good amount of processing power. Mayby amount of 10-20 computers would have much use for some work.

But hey.. that can be done! Look at clusterKnoppix for example. :)

Question?

Anonymous's picture

if i build a server, can i run old laptops as clients instead of desktops? i have a bunch of old laptops that are almost worthless, but have 200 to 350 Mhz processors in them. would these things work?

Re: Question?

Anonymous's picture

The short answer is YES.

The long answer- If the NIC is built in, then there should be no problem, you could treat it like any other PC (ie find the boot image you need at http://www.etherboot.org/db/ place it on a floppy, and boot from the floppy. )

If the NIC is a PCMCIA, then you would need to get the wireless package from the ltsp download page: (http://sourceforge.net/project/showfiles.php?group_id=17723), place it on a floppy and boot from that. The one drawback here is that the card has to be supported by Linux to work.

Any of the images can be placed on the hard drive as well, so you don't have to worry about floppies, but then of couse you have to worry about hard drives.

I have an OLDER laptop then what you mentioned, and have Linux installed on it. I partitioned the harddrive for 3 basic setups - To boot DOS, to boot the LTSP wireless image, and to boot into native Linux.

Re: Question?

Anonymous's picture

How hard is it to set this up? I like the idea of having the laptops be wireless. That would be a huge benefit.

Re: A Computer Lab with No Windows, Part I

Anonymous's picture

I've owned a PC300PL for many years and love the thing. I just moved it from the p2 350 to a 900 Mhz proc, and will be topping it off at 1.4 GHz hopefully this month. Given it's AGP slot and that fact it hold 768 MB RAM, this has been one of the most expandable and upgradeable machines I've ever owned. These are truly great machines, and it's no wonder they continue to be used everywhere!

Re: A Computer Lab with No Windows, Part I

Anonymous's picture

Great article. I did something similar in a northern rural school in Saskatchewan. That other OS was very unreliable. We had to reboot every class to keep any semblance of productivity. I ran the server 79 days without a hitch after we switched to LTSP. The point about memory is vital. I use 1.5 gB for 25 machines and I have had no problem. Linux caching of files really keeps the per-client demand for RAM down. I can use 1.5 gB with one user or 22. It's just the amount of cached files decreases with added users. It would be much cheaper than 64 bit to use two 32bit server IMHO. Of course, you can serve the whole school with a 64bit system plugged with 2gB RAM modules. After 100 or so, you may want more CPU power in the server... I also use gigabit to 10/100 switches so there is less likely to be a network bottleneck. See the .pdf at the bottom of the page here> http://www.skyweb.ca/~alicia

2 x 32 = .....hang on...

Anonymous's picture

"It would be much cheaper than 64 bit to use two 32bit server IMHO"

Right.....because everyone knows that 2 x 32 bit computers = 1 x 64 bit computer, right?

Uhh....ok, maybe not....but everyone knows that you can buy two xeons for the price of one opteron, right?

Well, no then.....umm....exactly what were you trying to say?

2X32 = 64

Anonymous's picture

It's not the bits but the CPU power. AMD64 3000 is only somewhat faster than XP 3000. If you are short of CPU power, it is much cheaper to get two 32 bit systems than one 64 bit system. You can get a good XP for about $100 but the AMD64 is about $180. Two 32s is faster than one 64 in this case. You pay a premium for 64 bit in the motherboard and CPU. The KT880 motherboard has four memory slots, so you can run 2 gB. You also get more redundancy with two 32 bit systems. One might manage the whole load in a lab when the other is down (rarely, I expect).

I have used AMD64 in 32 bit and 64 bit mode and XP2500 and, to the user, there was not that much difference. I prefer 64 bit as a server, of course, because it can really move a lot of data, but it is more expensive in purchase price.

Linux in education resources

Anonymous's picture

There is a thriving community of groups working with Linux in education. K12LTSP is one of these groups, but there are many more. Take a look at Schoolforge to see loads of member groups and resources. It's a good place to get your questions answered, too!

Re: A Computer Lab with No Windows, Part I

Anonymous's picture

OUTSTANDING!

I think a class involving the building of this lab alone would benefit IT students anywhere. I mean, wouldn't it be cool to offer a class "LAN101 Hands on LAN building" or "FA-Q-MS101 If you don't have skills, you're just and MCSE." Start with a closet full of "old" computers and design, build and administer classroom lab...

Re: A Computer Lab with No Windows, Part I

Anonymous's picture

Just exactly RIGHT. This BELONGS in the Linux Journal Magazine and as an online tutorial. I've nearly convinced some MS IT types at work not to scrap all the (100+) 233 pentium class machines they (we) are still running with NTsp6. I have shown in my own office the speed and stability gains of Linux (Debian 3.0 and XiG 3D Accelerated Xserver), oh yeah, they love the Open GL screensavers! So this project could really pay off, (as long as we can find a good replacement for Outlook with the calendar features), even the Pro-E guys in tooling design love VariCAD on XiG/ Matrox video cards. Oh and the Citrix server for BAAN could be mothballed, as BAAN is native UNIX! AND, think of the FEA analysis running on a Linux cluster!! YEEEEEEES. Matthew Victor

Re: A Computer Lab with No Windows, Part I

Anonymous's picture

Thank you for sharing your experience with us!
Question: Are your thin clients audio enabled (can they play xmms or noatun)? If yes, how did you achieve this (artsd?) and how is the sound quality (latency)?

Ok, thank you again.
JIS.

Re: A Computer Lab with No Windows, Part I

Anonymous's picture

Just saw this on fedora's webpage...

Fedora Core 1 for AMD64 test1 Available!

A test release of Fedora Core 1 for AMD64 is now available from Red Hat and at distinguished mirror sites near you, and is also available in the torrent. Like the original x86 architecture release, the AMD64 architecture has three binary ISO images and three source ISO images. This is a single (we hope and intend) test release specifically to check hardware support; the package set is the same versions as an updated Fedora Core 1 for x86 system will have. Please file bugs via Bugzilla, Product Fedora Core, Version test1, Architecture x86_64 so that they are noticed and appropriately classified. Hardware support bugs should generally be filed against the kernel component, unless they are specifically about kudzu or anaconda. Discuss this test release on fedora-test-list.

Re: A Computer Lab with No Windows, Part I

Anonymous's picture

At whatever scale, centralizing disks and system configuration saves a lot in terms of maintenance and system administration (much of which involves security issues).

My department recently installed a bank of (mostly dual-Xeon) Linux and Windows terminal servers backed by a fileserver that speaks NFS to the Linux and CIFS to the Windows -- all files are available from both environments. We run Linux on 500+ desktops, including six 30-station student labs. We used to provide Windows capability, where needed, via VMware but now provide it from the Windows terminal servers, which are accessible from Linux via rdesktop. As time goes by, the desktops will be minimally maintained and, perhaps, eventually eliminated in favor of personal portables. The cost of the servers, including the 1TB fileserver, was about the same as replacing the machines in one lab.

Adding failover and load balancing to LTSP

Anonymous's picture

Along these lines, a prototype system was implemented in a Colorado Springs elementary school that extends the LTSP approach with server failover and load balancing:

http://otero.harrison.k12.co.us/Linux/lab.html

A "howto" for building, deploying and integrating these systems with existing school infrastructure is available here:

http://theseus.sourceforge.net/projects/ets/ets-howto.html

-vlx

Distributed filesystems?

Anonymous's picture

I've seen quite a number of setups to solve similar goals (though I haven't built one myself). One of the things I've noticed is that if the clients are fast enough to run some things locally, significantly less load is put on the server, the machines 'feel' faster, and things scale better. This means the local clients need hard drives (or lots of ram). Now, there's all sort of setups you can do (e.g. KDE running locally, but all the buttons set to launch the programs remotely).

I won't bother discussing the benefits of different options here, them here. What I'm curious about is the use of a distributed filesystem such as code to give some of the benefits of a local disk, with few of the problems. If you view the local drive purely as a cache then coda appears to give all the benefits of NFS mounted / and /home, without the performance hit.

Sure, you will get more noise (especially with old drives), and local drive failures are a hassle. But you go from needing a very impressive server to needing a perfectly ordinary server and you don't have to give up the ease of maintaince.

My question is, has anybody actually done this? I have experimented with coda, but only for sharing files between users, not for mounting /usr

Re: Local drives not needed

Anonymous's picture

That is one of the best things about LTSP even with out a local hardrive you can still run apps locally using the 'Local_apps' pkg. It use an NFS mount for apps and runs them on the local CPU.

Re: Local drives not needed

Anonymous's picture

Cool, I didn't know that. Thanks :-)

Re: Distributed filesystems?

Anonymous's picture

In my experience as a student, a bit of latency when you're clicking isn't going to make or break your educational experience. A significant lag is annoying, but I've done transistor layout over a network in my school's solaris lab without issue. If my understanding of the software I was using (cadence) and the X protocol is correct, that would be much more burdensome on the server and network than basic web surfing and word processing.

As to scalability, it seems that he is memory limited rather than processor limited, hence the comment

"thus, for people who want to build a LTSP to support more than 30 workstations, 32-bit CPUs are out of the question--"

No mention is made of the processors, so I'm guessing they haven't been an issue. So with a larger memory address space, it should be possible that he could support more users on a single server.

As to the cost of the server, $4500 to support 30 stations is $150/station. That's it. When he needs more server resources for the next KDE/Gnome release, then he only needs to spend another ~$5000, if that much, and he has a complete system upgrade. If you build a system that relies on the clients you lose the key advantage to having a thin client system, in that your cost multipliers are low. Depending on the client using something like AFS means that the machines are once again tied to the upgrade cycle. If you're trying to get bang for the buck (and school systems are) that's not the way to go.

I've actually thought about trying to do something like this for a local school and imagined that the best setup would be a pair of dual opteron servers (or whatever, the 970FX looks nice but would probably be difficult to acquire) sitting next to each other and serving adjacent classrooms with ~25 terminals each. The goal would be to provide the servers with the resources to barely support the users of both classrooms. Based on the numbers in this article and others, I'm guessing that 8GB in each machine and a pair of 200GB SATA drives (one is for backup, stays unmounted most of the time) should do. Then put the two machines into a cluster so that one failing won't result in classroom downtime. This is entirely theoretical, so I'm interested in what the author would think about this kind of arrangement.

Re: A Computer Lab with No Windows, Part I

Anonymous's picture

Good Job! I used Linux and thin clients for 4 years while teaching at a school in Kentucky. We had two separate application servers and one file server. If an app server failed, then we could use the other (although slow with that much load). The only time an app server failed it was due to administrator error. Backups were done from the file server to the app servers so that is the files server failed (which it never did) we could still access the files.

Another advantage of thin clients is the elimination of noise. Hard drives make more noise than you realize. I never found a good (read cheap) solution to eliminate the noise of the power supplies.

Re: A Computer Lab with No Windows, Part I

Anonymous's picture

> I never found a good (read cheap) solution to eliminate the
> noise of the power supplies.

Depends what you mean by cheap. A PSU just one tier up from the budget range is really quite good. Sure, it isn't whisper quiet, but it may well be worth the extra $10.

Re: A Computer Lab with No Windows, Part I

Anonymous's picture

yeah it really sucks thier taking away linux at our school :(
good article though

Re: A Computer Lab with No Windows, Part I

Anonymous's picture

Hi, great article and my chance to post my question:

How do you do user-maintenance? How do you setup the user-environments for say each grade? How do you restore a damaged user environment? How do you make the user-environment so it can not be modified (like menu-items removed etc). How do you set it up so that the user can't leave his home-directory?

I'm facing the task of setting up 50 telecenters in rural areas in primary schools. LTSP looks very good. I have to train the administrators. Very little local knowledge available. So if you the author can help or anyone else it will be very much apreciated!!!

Peter

You should perhaps investigat

Anonymous's picture

You should perhaps investigate School District 73 in British Columbia, which has a very large group of linux computers running throughout their high schools and elementary schools. Or perhaps the Extremadura area of Spain, where they have installed 80,000 linux computers in their school systems, hospitals, etc.

Re: A Computer Lab with No Windows, Part I

Anonymous's picture

> How do you make the user-environment so it can not be
> modified

If you are using KDE, you will have access to the Kiosk framework which allows fine grained access to all of this. There is a GUI front end to it being written at the moment, but it's fairly easy to manage by hand as well.

Here's something I wrote on it in late '02: http://www.linux-mag.com/2002-11/kde_01.html

It's improved even since then, but you should be able to get the general idea....

Re: A Computer Lab with No Windows, Part I

Anonymous's picture

I don't know what kind of administrative GUI's have been written for school specific linux distros, but I do know that Linux makes all the tasks you've listed to be very simple to perform. One way you could get the setup you are looking for would be to store the windows manager's (ie. KDE, Gnome, IceWM, etc.) configuration for each grade in a system directory anywhere on the system, most likely somewhere under /etc, then, when you create a new user account, make sure a different symlink is created to link to the appropriate configuration depending on the grade of the student. In this way, the configuration files in /etc are write protected by default from regular users so the students wouldn't be able to alter the window manager's configuration. You could also do this for any other programs who's configuration you don't want to be modified and whose settings should be global among certain grades.

Of course, I'm sure tasks like this are simplified through whichever distro you choose to use and there is always plenty of support for linux projects on the internet. I'd say, just dive into it and work out each issue one by one.

All user maintenace would be done by logging in as root from any computer and using the administration tools that come with the distro and the programs that you choose to install.

The only person who could damage a user environment would be the administrator with root access, since you don't want students to be able to modify settings and if for some reason one of your settings caused the user environments to act unexpectedly, just undo your last change.

You can block users from viewing the system by taking the global 'read' permissions away from system directories (chmod 751), but there shouldn't be any reason for stopping students from viewing the system. It would be good for them to be able to explore the Linux file structure.

I'm not experienced with the LTSP setup, but that makes no difference because you only need to manage the one computer system with local user accounts. Everything is local to the one server. It makes everything incredibly simple.

Re: A Computer Lab with No Windows, Part I

Anonymous's picture

Goto www.k12ltsp.org and sign up for the email listserv. Redhat sponsers it and there are lots of folks on there who can help. Also you can use IRC at Freenode.net channel LTSP

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