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Felster
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Scrapping PCs for Pis in a London Comprehensive

Mon Mar 14, 2016 10:08 am

Hello all,

We're taking the plunge this year and entering all of our students onto the Computer Science GCSE rather than ICT. As part of that I'd like to gut a lot of our decrepit old IT rooms and turn them into spiffy new Raspberry Pi Computer Labs.

We'd set up one RPi to a screen, with no PCs to be found (other subjects would have their own PC rooms). Networking would be managed through PiNet, and we'd use Libre Office whenever we needed to create documents.

Has anyone got experience with this? What are the issues I'm likely to encounter, and is there something I'll realise I desperately needed those PCs for the moment I turn them into paperweights?

Thanks!

W. H. Heydt
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Re: Scrapping PCs for Pis in a London Comprehensive

Mon Mar 14, 2016 2:04 pm

Keep one PC to use for re-flashing SD cards.

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DougieLawson
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Re: Scrapping PCs for Pis in a London Comprehensive

Mon Mar 14, 2016 4:40 pm

W. H. Heydt wrote:Keep one PC to use for re-flashing SD cards.
That's the primary function of PiNet, it runs on a regular Linux X86 machine and delivers software to the Raspberries that are booted with a "read-only" SDCard.

The main thing to look for is DVI-D monitors with HDMI to DVI-D cables (not adapters), they're cheap, common and work really well with ALL models of Raspberry.
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Felster
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Re: Scrapping PCs for Pis in a London Comprehensive

Tue Mar 15, 2016 8:30 am

Thanks both,

I'm pretty sure we use the HDMI / DVI adapters already for other reasons, so that should be an easy sell. Something like these?
http://www.ebuyer.com/130512-xenta-hdmi ... &pkw=&pmt=?

hippy
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Re: Scrapping PCs for Pis in a London Comprehensive

Tue Mar 15, 2016 1:07 pm

Felster wrote:What are the issues I'm likely to encounter, and is there something I'll realise I desperately needed those PCs for the moment I turn them into paperweights?
I would imagine the biggest problem will be if students, staff or your courses require or desire the ability to run X86 software which is not also available for ARM.

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Felster
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Re: Scrapping PCs for Pis in a London Comprehensive

Tue Mar 15, 2016 2:13 pm

That's the big question isn't it.

I'm fairly confident we can teach Computer Science without any software other than the basics included, the concern would be if there's some dynamite new product that comes out in a few years that we don't have access to. A lot of new edu technology seems to be aware of that though and runs through a web browser, e.g. flowchart plotters or the Micro:bit.

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morphy_richards
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Re: Scrapping PCs for Pis in a London Comprehensive

Wed Mar 16, 2016 6:50 pm

What board are you looking at using?
If you check the requirements for the 2016 qualification it should tell you what's needed. That's unlikely to change for a few years. I had no problems doing WJEC computer science which involves Java ("Greenfoot") and "any suitable general purpose language" which ended up being Java and Python. That worked fine on 30 networked Pi Bs.
I know OCR sometimes asks for a task to be completed in App Inventor. I don't know how that might work on a pi but in theory it should work I suppose

I'm also in an inner city London comp. You are welcome to come and see our setup if you pm me we can arrange something if you like.

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Felster
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Re: Scrapping PCs for Pis in a London Comprehensive

Thu Mar 17, 2016 6:39 pm

Morphy, that'd be great. I'll pop you a pm now.

We're currently with AQA, but I think I'll jump ship to OCR for the new spec - AppInventor is definitely out for them, we'll be running Python.

Gbaman
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Re: Scrapping PCs for Pis in a London Comprehensive

Fri Mar 18, 2016 1:18 am

Glad to hear you are interested in using PiNet. PiNet includes support for ltsp-remoteapps. It is a feature that is still pretty experimental (hence why isn't shouted about much), but it allows you to run applications on your server, then nicely forward them to the Pis, where they appear as native applications. It is very far from perfect, but from my own tests seem to work quite nicely.
Details can be found over on the Remote Applications documentation page - http://pinet.org.uk/articles/advanced/remote-apps.html
Be warned, needs a powerful server, but means may be even less you can't do with Pis now.
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morphy_richards
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Re: Scrapping PCs for Pis in a London Comprehensive

Fri Mar 18, 2016 8:15 am

Interesting. You can build "powerful" servers for about 100 quid if you just use a generic motherboard and AMD type multiple core processor. You can even pick up 8 Gig + of RAM for next to nothing.

When I first started out I went down the LTSP route, it worked really well (at first) programs on the 'server' ran nicely on the pi's which were acting purely as thin clients.

I used an AMD 8 core processor, can't remember exactly what it was and 8 Gig of generic RAM in a cheapo case.
What didn't work so well was when the graphics were looking for hardware acceleration.

Also when 30 kids all tried to do intensive things simultaneously the server would reboot out of nowhere. I'm fairly sure that was the Power Supply, I think it was 350 Watts and couldn't quite cope with all 8 cores at 100%

Using pi's as fat clients / ltsp-remoteapps as in your pi net would definitely ameliorate that.

Also my current LDAP file and login server is based on something called Zentyal 2 Community edition. They've stopped supporting that now that 3 is out but have made changes so that upgrading would involve significant changes to everything else.

Again your pi net is much better here as it is a simpler solution that works straight out of the box.

Could you theoretically use a pi net server with other Linux based computers that are not rpi's? Not for fat client capabilities but to handle login and file storage?

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Felster
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Re: Scrapping PCs for Pis in a London Comprehensive

Sat Mar 19, 2016 8:43 am

I hadn't spotted the remote apps - but that's good news. That takes some of the pressure off the decision. PiNet was the missing piece of this puzzle so thanks for your work there.

Server wise I'm hoping we can repurpose one / part of our existing PC servers. We'll be decommissioning ~ 100 PCs if this goes forward so we'll be freeing up some capacity.

ejolson
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Re: Scrapping PCs for Pis in a London Comprehensive

Thu Jun 09, 2016 4:19 am

Felster wrote:Server wise I'm hoping we can repurpose one / part of our existing PC servers. We'll be decommissioning ~ 100 PCs if this goes forward so we'll be freeing up some capacity.
The Pi 3 makes a great device for connecting wires and controlling other devices. It is also small and can run from batteries in mobile applications. However, It does not make a good desktop computer because it has limited RAM, limited I/O speeds and a tendency to overheat.

Are the lab PCs less than 8 years old? Are their HDs larger than 64GB? Do they have more than 1GB RAM? If the answer is yes to these questions, then those PCs are better desktop computers than the Pi 3. Installing Linux or configuring them as fat LTSP clients would make them seem like new and allow you to save the Pi computers for the physical computing projects that only they do well.

insanityideas
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Re: Scrapping PCs for Pis in a London Comprehensive

Mon Oct 17, 2016 4:19 pm

Did you go ahead with junking the PC's and going with Pi3 in the end?

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