RasPi as a basic school desktop replacement

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by TrevorB » Sat Dec 03, 2011 3:20 pm
I totally get the idea about invigorating the teaching of proper computing in schools and I am right behind that, but as a UK school leader, I have an even more pressing problem.

I have three IT rooms in a secondary school with 90 computers running MS Windows/Office which are all so slow they are unusable and with very old and failing monitors as well. I also have virtually no money to replace them thanks to bad financial planning by a previous regime.

[color=#FF0000]What would it cost to replace them?[/color]
90 PCs x £400 inc licences & monitors = £36,000
The cost of 3 year's electricity with a PC power supply of 0.3kW and a monitor of 0.15kW on for 8 hours per day for 200 days per year @ 10p per unit
= 90 * 0.45 * 8 * 200 * 3 * 10p = £19,440

That's a three year cost of over [color=#0000FF]£55,000[/color] (I'm assuming a three year replacement cycle here). We don't have the money. I could lease, yada yada yada, but we're on our uppers. Really.

[color=#FF0000]If I could get RasPis instead,[/color] it would be a lot cheaper
90 RasPis * £22 = £1,980
90 new hard glass monitors @ £85 = £7,650
90 microUSB power supplies @ £5 = £450
90 HDMI to DVI-D converters @ £5 = £450
90 miniHDMI to HDMI cables @£5 = £450
and at a power rating of 0.005kW for the RasPi and 0.05kW for the monitor, three years electricity is
= 90 * 0.055 * 8 * 200 * 3 * 10p = £2,376 (Big reduction!)
Total cost is [color=#0000FF]£13,356[/color]
I can afford that much.

My only problem is that our desktop is Windows and all our tech expertise is Windows. We could move our storage to the cloud but we would need to authenticate logins against a Windows Server active directory.

The financial case seems very strong to me.
It wouldn't be nice for teachers who all have their fave educational program that only runs on Windows, but these labs are almost exclusively used for web browsing, word processing, powerpoint making and occasional spreadsheets. Any other school leaders seduced by the idea?
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by obarthelemy » Sat Dec 03, 2011 3:42 pm
Sounds nice indeed.
I'm a bit confused about your cables dance. I assume your monitors are DVI-D or -I, the Pi is full HDMI, a simple HDMI to DVI cable works, what is the miniHDMI to HDMI dongle doing in there ?
On the other hand, you might have forgotten about the SD cards, keyboards, and mice ^^
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by SeanD » Sat Dec 03, 2011 5:51 pm
There will be additional costs but you should investigate a VDI based solution which is becoming very common in education for many of the reasons you list above plus it has the benefits of removing many of the endpoint management issues. You can for example start every session with a clean OS image. There will be server and additional software costs but I suspect the RPi would make a great thin client, and it would be available for local computer science education as well which is more in line with its design goals.
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by scep » Sat Dec 03, 2011 6:13 pm
90 HDMI --> DVI cable £100
90 keyboard and mouse: £450
100 SD cards: £200
..saving £150 to be spent on the ICT department staff party.

I think we'll see this general model in schools within the next five years (not necessarily with the Pi of course, could be one of its many imitators ;)). The electricity use alone will be the clincher for most acadamies (who must now run as a business and care about such things :)) never mind the hardware and software costs. We have several hundred PCs in our school, so multiply that juice bill up by a factor of 5.

Yes, change will happen. I expect a paradigm shift (educationally speaking) about this time in 2013.
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by bradburts » Sat Dec 03, 2011 6:27 pm
Its a great idea.
The Linux desktop should be easy enough to use.
Open Office is just like Office, even the menus are in the same order!
Google apps are taking over the world so if you have the broadband that part is easy as well.
You should be able to get a Linux Live CD (boot from CD) from a magazine and have a go before your RPI arives.
The VDI idea is the right way to go, but thats a few experiences along.
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by TrevorB » Sat Dec 03, 2011 7:33 pm
Hi All,

Thought the HDMI socket on the RPi was miniHDMI and I couldn't find a miniHDMI to DVI-D cable

I don't know what VDI is - could someone help me there?

I've been investigating open source in UK schools and haven't found a single school currently using it on the desktop! Perhaps there's a school leader out there using OSS who can put me right?
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by Eclipse » Sat Dec 03, 2011 7:34 pm
The power consumption figures for your existing computers are probably a little off. The power supplies might be rated at 300W, but the computers you described shouldn't be using anything close to that. Of course, the savings will still be significant.

For light (non-multimedia) web browsing and document creation, the Raspberry Pi should be able to cope. However, tools such as OpenOffice are evolving all the time and it's not impossible to imagine a situation a year or two in the future when the software becomes too much for your hardware to manage.

Other items to add to your shopping list:
    ? 90 USB hubs
    ? 90 cases
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by SeanD » Sat Dec 03, 2011 8:58 pm
Quote from TrevorB on December 3, 2011, 19:33
I don't know what VDI is - could someone help me there?


VDI (Virtual Desktop Infrastructure) is one of those technologies that has been around for years but due to certain technologies aligning is just starting to take off in a very big way. How it works is that the users actual desktop runs on a centralized server along side everyone else desktops and a "thin client" which is really a low powered computer that does not have needs for local storage etc. (as all it is doing is rendering the UI from the central server and dealing with the human interaction (keyboard, mouse, display). The thin client could be something like and RPi, an older less powerful PC or laptop, a tablet or a smartphone (although there are currently some nuisances with devices that do not have real keyboards).

Many universities, large schools and enterprises are either investigating or rolling out this technology today. I have also seen it deployed in elementary schools here in the US to reduce upgrade costs.

Obviously the server that sits at the center must be pretty powerful but because of they way that resources are shared and the kinds of workloads (such as teaching ICT) do not strain the processor very hard it is possible to get very high densities (the measure of numbers of virtualized desktops sharing a server or processor) as long as you have sufficient memory from pretty modest kit. Trying VDI for complex mathematical modeling, video rendering etc. will be a world of pain but ICT activities are fine. The other advantage is that it can also be used with BYOD (bring your own devices) as all you need is the client and the credentials to be able to access the resources on your own device.
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by abishur » Sat Dec 03, 2011 9:39 pm
Nice idea there Sean, it would allow for MS environments to move to linux without loosing all the programs schools have come to rely on.
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by obarthelemy » Sat Dec 03, 2011 9:54 pm
VDI = Remote Desktop on an industrial scale, a dumb terminal on one side serves as display and keyboard for programs actually running on a server that runs tens or hundreds of terminals. One of the main issue up to now was that that so-called "dumb terminals" actually cost as much as a regular PCs (thanks, Wyse ^^). Hopefully the Pi can solve that. It has the hardware to run the Citrix / MS / VMWare clients, and I'm fairly sure at least Citrix exists in ARM flavour, hopefully it'll run on the Pi.
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by hlt32 » Sat Dec 03, 2011 10:51 pm
Bear in mind you'll still need a Windows license for each virtual machine you run, and hardware to run your virtual desktops.

Then take into account the increased maintenence costs associated with staffing - you now need to maintain staff to manage the servers, the virtualisation environment, AND the linux environment (in addition to the standard windows administration).

I'm not convinced you'd actually save that much money, if any at all.
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by obarthelemy » Sat Dec 03, 2011 11:17 pm
Actually, you do, a bit.
- Windows licenses can be bought on a "max concurrent users" basis, instead of per PC.
- servers admin must indeed be done. They shouldn't need separate admin staff though, and once setup don't need much work. The virtualization environment does require specific skills though.
- the linux machines require much less admin, not so much because Linux is more reliable (though it is, and users have less room to break it), but because they do so much less, and you can cheaply keep a handful of spares so that broken units can be swapped and fixed during spare time, not as a top priority.
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by Davespice » Sat Dec 03, 2011 11:24 pm
The remote desktop solution would probably work quite well, all you would need to install on the Raspberry Pi's would be Remmina Remote Desktop Client. Then all the domain level authentication is done by the server.

If you wanted to use Linux as a desktop productivity environment though it is possible to set up Linux to authenticate against an Activity Directory. You just need to install samba, the windbind daemon and change a few settings. This ubuntu page was quite helpful when I did this.

It's also a good point about having to pay for Microsoft Software licenses, with Linux everything is suddenly free forever. So that would certainly translate into a cost saving over time.
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by hstubbs3 » Sat Dec 03, 2011 11:52 pm
Ugh.. Windows VMs under XEN or KVM just seem ugly to me. . let alone the server licenses..

Multiple terminal sessions into a big windows server seems like it would work better...
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by Point3Forever » Sun Dec 04, 2011 12:05 am
I just want to chime in about maintenance costs. My school's IT work is all done by students in a computer technology/engineering class. Most set-up reformatting upgrading etc. is done by students. They learn, school profits.
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by jamesh » Sun Dec 04, 2011 9:05 am
Quote from Point3Forever on December 4, 2011, 00:05
I just want to chime in about maintenance costs. My school's IT work is all done by students in a computer technology/engineering class. Most set-up reformatting upgrading etc. is done by students. They learn, school profits.


I'd be checking those machines for keyloggers!
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by Sylvain » Sun Dec 04, 2011 10:11 am
Quote from Eclipse on December 3, 2011, 19:34
The power consumption figures for your existing computers are probably a little off. The power supplies might be rated at 300W, but the computers you described shouldn't be using anything close to that. Of course, the savings will still be significant.


Hi,

In fact, these figures are not for me "a little off" but completly off.
I'm quite interested in computer power consumption and I do test a great part of the computers I assemble/sale.

What I can conclude from those tests is that average "recent" computers (intel/amd dual core, IGP or simple graphic card, only one HDD ...) rarelly even reach 100 W at full load and half of that at idle.

Taking consumption into account when assembling the computer (core i3, Mini-ITX MB, low voltage memory, SSD ...), allows quite easily to be under 50-60W at full load and half or a bit less at idle.

For example, I have ITX I3-340/2Go/SSD/Win7pro PCs that work ~10 hours, 6 days a week with 65W PSU since 18 mounths, without any problem. I now use I3-21xx-T that consumes even less.

It's the same for the monitor where you should count 1/3 of what you are saying (ie. 50W) for a 22" screen, even less for a LED backlighted one. Some 24" LED monitors are rated under 30W by there manufacturers but I haven't tested that for the time being.

RasPi should still consume a lot less but don't forget that does not mean it has the best performance per Watt (see topics about distributed computings).

Finally, I am still cautious about using RasPi as a desktop replacement (RAM, no audio inpout ...) in non third word countries but I could change my mind after real tests ...

Sylvain.
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by TrevorB » Sun Dec 04, 2011 2:03 pm
Quote from Sylvain on December 4, 2011, 10:11
What I can conclude from those tests is that average "recent" computers (intel/amd dual core, IGP or simple graphic card, only one HDD ...) rarelly even reach 100 W at full load and half of that at idle.


I'm not sure what you're counting as "recent". The PCs I am struggling with are around 7 years old, single core. You talk about running machines with a core i3 and SSDs - these are completely beyond our school budget!

Quote from Sylvain on December 4, 2011, 10:11
It's the same for the monitor where you should count 1/3 of what you are saying (ie. 50W) for a 22" screen, even less for a LED backlighted one. Some 24" LED monitors are rated under 30W by there manufacturers but I haven't tested that for the time being.


For the original monitors, I'm working with old technology - CRT actually. I think they are pretty energy inefficient. Maybe I should measure them - I could get a power meter from the science department. For the new ones, I just took the power consumption ratings from manufacturers site.

Anyhows, even if I ignore any savings from electricity, I'd still have a desktop replacement scheme costing less than £11K over 3 years instead of £36K. For me the question is to go down this route or something similar, or simply remove the old PCs - I really can't afford to replace them given our budget situation.

Trevor
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by Warringer » Sun Dec 04, 2011 2:25 pm
I'd keep one or two of the old machines and use them to run a file server and maybe a webserver for the students to muck around with. Would only allow them to learn much more.

Besides moving to Linux is not that much of a problem anymore, compared to, say, ten years ago. Today most programs have GUIs for daemons and other tools that used to be command line only.

Hey, with 22 pound per unit, you could ask the kids if they want to buy one of those little beasts for themselves. That way you only have to have monitors, power supplies, network access and mouse/keyboard.

Through there should be a couple of Pis around for the kids that don't own one themselves.

And that is actually one of the goals of the Foundation.
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by Sylvain » Sun Dec 04, 2011 3:24 pm

I'm not sure what you're counting as "recent".


Something under 3/4 years old.


The PCs I am struggling with are around 7 years old, single core.


OK but you were speaking about replacing them, so I take into account the consumption of the new ones ... Shouldn't I ?


You talk about running machines with a core i3 and SSDs - these are completely beyond our school budget!


Since the "Core generation" Celerons (G530 ...) exist, it's the kind of PC you could have with the budget you were giving (400£), if you chose linux like for the RasPi.
All the way, that's not really the problem here ...


Anyhows, even if I ignore any savings from electricity, I'd still have a desktop replacement scheme costing less than £11K over 3 years instead of £36K. For me the question is to go down this route or something similar, or simply remove the old PCs - I really can't afford to replace them given our budget situation.


OK, BUT the problem is that, depending on your real hardware(*), there are many chances that its theorical cumputing power is already comparable or higher than the one of a Raspi (except for specific things like decoding videos, 3D and so on ...). That's why I do not see RasPi as a real desktop replacement for now in non third world countries, maybe a thin client but it implies other problems/costs.

Further more, for me, an "only" 7 years old PC becomming "unusable", is not normal. There are of course many reasons for that (lack of RAM, virus/bad antivirus, full/fragmented HDD...) but also unexpensive/free solutions. I spend a part of my professional time (for nearly free), making "old PCs" work as they should work, including for schools.

Besides, my main personal (and professional) PC is a bit more than 8 years old today and it's perfectly usable for much of the thing I do (I have a 2 years old linux PC for things that really need a lot of computing power, but I don't use it so much).

Sylvain.

(*) : For 7 years old PCs, I estimate something like 2 GHz / 512 Mo / 40 Go / XP
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by obarthelemy » Sun Dec 04, 2011 4:11 pm
I think you should do a 3-way study of costs including investment and running costs over your budgeting cycle:
- current setup, with required upgrades and manpower to clean years of accumulated junk.
- low-end x86. Intel is keeping the Celeron and Pentium brands alive in the low end; differentiating mainly by support for virtualization, GPU, and cache size (on top of cores and frequencies of course). You do benefit from lower power requirements, CPUs are in the 35-65W range (I'm assuming Atoms would be too underpowered). AMD have some good stuff too in the low end, better graphics, lower cost, but more power consumption. I'm using an E-350 as my main desktop personally, it is OK.
- Pi with all required doodads, and Windows servers for the users that need Windows software.

The easy stuff is the initial costs and power budget. The hard stuff is the support costs and features tradeoff (as in Windows with its software, viruses and user knowladge, vs Linux with its stability and required Windows session server).
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by TrevorB » Sun Dec 04, 2011 6:06 pm
Quote from Sylvain on December 4, 2011, 15:24
OK, BUT the problem is that, depending on your real hardware(*), there are many chances that its theorical cumputing power is already comparable or higher than the one of a Raspi (except for specific things like decoding videos, 3D and so on ...). That's why I do not see RasPi as a real desktop replacement for now in non third world countries, maybe a thin client but it implies other problems/costs.

Further more, for me, an "only" 7 years old PC becomming "unusable", is not normal. There are of course many reasons for that (lack of RAM, virus/bad antivirus, full/fragmented HDD...) but also unexpensive/free solutions. I spend a part of my professional time (for nearly free), making "old PCs" work as they should work, including for schools.


That's interesting. They certainly are unusable, so I think my next step is to find out exactly why that is. If as you suggest, it isn't about raw computing power, I'll have to think again.

My feeling is that the sheer weight of the Windows OS/MS Office apps/IE was weighing down old hardware. Hence something that introduced a lighter OS/office apps/browser combo made sense. I could just install linux on the old hardware, but the CRTs are getting knackered and I thought the energy saving would be significant too.

Time to check the specs I think and also whether there are networking problems slowing down the connectivity.

It'll take me a couple of days to find out the specs, but I'll post back again.
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by Jessie » Sun Dec 04, 2011 6:29 pm
There have been a couple schools here in the US and some in Germany (I know the government there tried it as well) that tried switching to Open source software and all of them changed back quickly. I don't know much about them but from what I gathered their "IT" department couldn't handle whatever version of Linux or BSD they were using. To put it simply there are many IT hacks out there and simply blaming the OS and software is an easy way to cover their incompentencies to their superiors.
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by SlyFoxy » Sun Dec 04, 2011 6:54 pm
In this instanse the best thing is to have a RasberyPi's as dumb terminals, I'm pretty sure you can find some good open source windows desktop terminal software which would do most of the tricks, then all you need to do is set up your active directory as a termianl server (does require liscening, but you can set it at say 100 machines and that's not to massive a cost) the issue for this can be network infrastucture and if you server isn't too up to spec it's not great. I think the rasberryPi is abit of a dodgy choice, sadly most people don't feel open source is too great still and would rather stick to MS solutions.

Another option tho, if your wanting to use them purely for Office/Web Browsing... get a very simple linux distro or wait for chromium to get ported and use google docs, they're probably happy to provide email web services to school at a very competitive price plus with Google as a big brand name people weren't gawk so much at the idea compared to choosing open source solutions.
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by obarthelemy » Sun Dec 04, 2011 7:35 pm
You don't need Chromium for Google Docs, any reasonnably modern Browser should work. Opera and Firefox do, and most browsers are based on Firefox's or Chrome's engine anyway.
You DO need backups though, and the one tool I could find to do it is for pay and fairly expensive ($15 I think).
Deep down, I really can't fathom how a web app can be preferable (quicker, more full-featured, or more ergonomic) to a regular app. I think that says a lot about MS Office and LibreOffice, mainly ^^. I've got a topic somewhere about lightweight desktop apps for the Pi.
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