back to article New guide: Bake your own Raspberry Pi Lego-crust cluster

Scientists at the University of Southampton have built a "supercomputer" from Raspberry Pis lashed together to form a colourful data-cruncher. Professor Simon Cox and his team racked up 64 credit card-sized Pis using Lego building blocks to create the parallel computer. They named their beast Iridis-Pi after the university's …

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  1. Captain Underpants

    Excellent! I've been wanting to tinker with MPI on a 5-Pi Punnet for a while, so this will come in handy :)

    1. wowfood

      I always wanted to build a web server using a cluster of Pi, but turned out after reading a few things online it's less than satisfactory. Instead I'm waiting for the Ouya, sure it costs 3 x more, but it has twice the RAM, and four times the cores. I figure what I would have spent on Pis, I can grab four Ouya, and use a pair of Pi for load balancing.

      1. Eddy Ito Silver badge

        "Instead I'm waiting for the Ouya..."

        For a few bucks more you don't have to wait. An Odroid X carries Samsung's quad core Exynos 4412 and goes for $129. Sure the $40 shipping from Korea stings a little bit but it goes down per board when you get multiples. The ones I ordered took about two weeks to deliver, now I just need a free weekend to play with them.

  2. Valerion

    My Pi

    Is still in the box, because I can't think of anything to use it for.

    I need a better imagination!

    1. Anonymous Coward
      Anonymous Coward

      Re: My Pi

      At the very least find a mame port, blu-tack to the back of the tele and play pac-man.

      1. dont care what ever
        FAIL

        Re: My Pi

        he can`t have ordered them from rs , :)

        13 weeks and still waiting but ONLY another 4 to go (or so they say ) :)

        but its not like we have already paid for them .........oh hang on

        1. Danny 14 Silver badge

          Re: My Pi

          XBMC for Pi (Raspbmc). They are small enough to put inside your TV.

        2. Spasch

          Re: My Pi

          Ha! CPC tweeted this morning that they've got stock.

        3. James Gosling
          Unhappy

          Re: My Pi

          Me too! Is it this guy using up all the available stock that stopping me from receiving my Raspberry Pi?

      2. Pet Peeve
        Thumb Up

        Re: My Pi

        Have we gotten to the point where a $35 computer can play mame games without massive frameskipping? I've been out of the mame scene for a while. Years ago, I built my own arcade control box (with movable buttons and joysticks) that plugged into a computer (hacked keyboard). it would be cool as hell if I could put the whole computer in there too!

        1. pPPPP

          Re: My Pi

          Apparently it will do some of the older mame games, but then again, you need a lot of beef to play the latest ones. The point of the mame project is accurate emulation rather than playability after all.

          I got mine a few days after ordering from Farnell. Got it last week and it's now running OpenVPN through my router, so I can get into my home network when I'm out and about. It's got a 32GB flash card in it, which is plenty, and I can also wake up my other computers using WOL. Just need to get rsync up and running.

          I was hoping to connect an old web cam to it but it draws too much current. Might try a powered hub but I expect a more modern web cam would make more sense.

          I've always used Slackware and it seems to work fine on the Pi.

    2. Simon Collins
      FAIL

      Re: My Pi

      Got mine in the first batch. Lost it within a week. Think I threw it out.

      Oops

  3. Mondo the Magnificent
    Thumb Up

    Genius..

    I was wondering when someone would cluster the PIs, buut using Lego as a cluster rack just makes the project a whole let better..

    Well done!

    1. Dodgy Geezer Silver badge
      Coat

      Re: Genius..

      I can remember when that support would have been made out of Meccano.

      And there would have been lots of brass gears....

  4. Prof
    Holmes

    Jolly Good! How fast/powerful is it though?

    Are there any reg-standard benchmarks to compare it with?

    1. Pet Peeve
      Boffin

      I don't think there's a reg has a supercomputer benchmark yet (I'm thinking a good measure of FLOPS is the "facebook IPO"), but 72 teraflops would have qualified as a supercomputer as recently as 2007 or so (the Cray XT4 was about this fast). It's certainly nothing special now in terms of performance - a modern xeon workstation would be a couple of orders of magnitude faster at least - Moore's law does horrible things to 5 year old technology.

      Still, really cool, and the lego processor rack is nifty.

      1. John Brookes
        Stop

        Think you're a little confused....

        the 72TFl/s machine is the Iridis supercomputer at Southampton Uni, not the pi cluster. 72 is well in top500 range and _definitely_ a supercomputer.

        1. This post has been deleted by its author

        2. Pet Peeve
          FAIL

          Well, crap!

          Yeah, I made all sorts of mistakes here. I thought the 72TF number was the measured speed of the pi cluster.No speed number is given, as you say, that's the speed of their locally-built supercomputer.

          And then I got giga and tera reversed in my head when I was trying to fit the speed on the top500 list, and divided the speed by a thousand, oops! 72TF would be about 415th on the top500 list, and about 3 orders of magnitude faster than a modern xeon workstation. Never mind!

          The only reason I'm not withdrawing the original message is that I think "facebook IPO" as a measure of FLOPS is still pretty finny.

          1. Oolons
            Go

            Re: Well, crap!

            According to the rasberry pi forum one board manages 26 GFLOPS... So 64 would be 1.7 TFLOPS if it scaled perfectly. I also think that is including the GPU horsepower so translating that to real world performance and distributing across a cluster would not be easy.

            1. greensun
              FAIL

              Re: Well, crap!

              Would it have been too much for the "Journalist" to ask Professor Cox for this figure ?

      2. Stoneshop Silver badge
        Boffin

        @Pet Peeve

        I don't think there's a reg has a supercomputer benchmark yet

        I propose the 'Speccy'.

        1. Naughtyhorse

          Re: @Pet Peeve

          i counter the 'jordan at 40' cos that will deffo be a terror flop when she whips em out

      3. Andus McCoatover
        Windows

        Please, don't measure intelligence in FLOP's

        Reminds me too much of an old, historical Finnish phone company....

      4. Allonymous Coward
        Thumb Up

        I'm thinking a good measure of FLOPS is the "facebook IPO"

        ^-- upvoted for this

  5. geekclick

    How many lego blocks..

    hold it all together? This is important stuff El Reg!

  6. Anonymous Coward
    Anonymous Coward

    Or...

    ...you could just link 4 quad-core Mac Minis with a 5-port gigabit switch, and have something which is smaller, more reliable, uses less power, and probably just as cheap once you've allowed for network switching and lego. But not as colourful.

    1. paul 97

      Re: Or...

      Doubt it would use less power or perform parallel tasks better. A quad core is not the same as 4 different CPUs.

      At least if one of the raspberry pi's dies , its pretty cheap to replace.

    2. FreeTard

      Re: Or...

      What? The pi uses less than 4 watts at full tilt, and a quad-core macmini uses 85 W

      http://support.apple.com/kb/HT3468

      64 * 4 = 256 watts

      4 * 85 = 340 watts

      So your wrong :)

      1. Chris007
        Trollface

        Re: Or... @FreeTard

        FYI

        Should be "So you're wrong"

    3. Dan 55 Silver badge
      Trollface

      Re: Or...

      If anyone wants to rack-mount Mac Minis for their enterprise applications, Lego seems perfectly suited to the task. Only black, white, and grey pieces mind.

    4. P. Lee Silver badge
      Facepalm

      Re: Or...

      It's a university. They are there to research and teach principles and techniques, not extract maximum performance.

      Sometimes the point is is the doing, not the results.

  7. SoupDragon
    Headmaster

    One Pi is Pi

    What is the plural of Pi,

    I vote for Pice (better than Pis IMO) Raspberry Pis sounds more like something you get after eating too many beetroot.

    likewise should the collective noun be 'a circle'?

    1. CowardlyLion

      Re: One Pi is Pi

      The collective noun for Raspbery Pies is a punnet.

      1. Anonymous Custard Silver badge
        Joke

        For me, more than one Raspberry is

        Dessert :)

      2. Anonymous Coward
        Anonymous Coward

        Re: One Pi is Pi

        I thought a cluster of Pi's was going to be called a bramble? - that seems to be the most common term.

        1. Kubla Cant Silver badge
          Headmaster

          Re: One Pi is Pi

          To be pedantic, a bramble is a cluster of blackberries. I suppose a cluster of raspberries is a "cane", but it's not a very inspiring name.

          1. Michael Wojcik Silver badge

            Re: One Pi is Pi

            I suppose a cluster of raspberries is a "cane", but it's not a very inspiring name.

            You could refer to a cluster of raspberries on canes as a "brake", from "canebrake". That's roughly equivalent to bramble. "I'm doing the decoding with a brake of 8 Pies."

    2. TheOtherHobbes

      Re: One Pi is Pi

      Pixen.

    3. hplasm Silver badge
      Happy

      Re: One Pi is Pi

      Pies.

  8. Skizz
    Pint

    Nothing to say really...

    ...just raise a pint to those profs at Southampton Uni (from the Hobbit pub). Excellent.

    Perhaps the Pi can be used as the standard unit of super-computing performance?

    1. Anonymous Coward
      Anonymous Coward

      Re: Nothing to say really...

      @Skizz

      The Hobbit? Wow, is it still going... Must be 15 years since I used to stop by there on a Friday night crawl! Is The Dungeon still going strong too?

      1. Victor Ludorum
        Pint

        Re: Nothing to say really...

        The Hobbit is still going, despite a legal threat from some US company that claims to have the rights for the name from Tolkien. They even set up a Facebook page to fight the injustice.

        1. BorkedAgain
          Pint

          Re: Nothing to say really...

          ...and here's a link to the relevant page, in case you feel like weighing in with your support...

          http://www.facebook.com/SaveTheHobbitSouthampton

          1. P. Lee Silver badge
            Holmes

            Re: Nothing to say really...

            > hey even set up a Facebook page to fight the injustice.

            So they're doomed then...

        2. Fibbles

          Re: Nothing to say really...

          From what I remember, they didn't get sued for the name. It was using pictures of Elijah Wood et al, taken from the LotR films, on their promotional material and menus.

  9. ISYS
    Thumb Up

    Very nice but what have they actually done with it? How fast is it?

  10. David 14
    Thumb Up

    Great.. .but better ways to do the power...

    I love this implementation, and the link to the UNI blog was a fantastic step-by-step on the IT install, and even some good pics to use as a Lego guide... :)

    One thing I will say, is that for a group of techies, they really didn't get creative with the power supplies! That many power strips and each RPi getting it's own mains-connected adapter?

    One fo the great RPi features is the simple, 5v DC power input... any old 5v will work when pinned properly to a proper USB cable... so I would believe that a single DC adapter capable of providing sufficient amperage at 5v would work fine...

    The RPi, I believe, will demand up to 500mA... if that is the case, they would need to be able to provide 32A of 5v power... something that should be able to be done with at least just a few old PC power supplies, or even just 2 enterprise grade server power supplies from old servers... very little involved in splicing in the required octopus of cables needed for the multiple drops... but would be more efficient, for sure, and much less complex.

    Cheers!

    1. tommitytom

      Re: Great.. .but better ways to do the power...

      I'm not sure if this is what you are referring to?

      "The Debian GNU/Linux cluster runs off a single 13-amp mains plug"

      1. tommitytom

        Re: Great.. .but better ways to do the power...

        Scratch that, I just clicked on the link and saw the many multiplugs.. hah!

    2. Nigel 11

      Re: Great.. .but better ways to do the power...

      A PC power supply will be VERY unhappy supplying many amps at 5V and none at 12V. It may refuse to work with that load, overheat and emit smoke, or simply waste a large fraction of the power going in. They're designed for use with modern PC hardware, with the lion's share of the power being consumed at 12V.

      Just source a single-voltage power supply that delivers enough amps at 5V. There will be plenty of PSUs to choose from at RS or CPC. It may be cheaper to use multiple 5V 4A or 5A "bricks" than a single (say) 40A unit, and may also be easier to wire up.

      1. Anonymous Coward
        Anonymous Coward

        Re: Great.. .but better ways to do the power...

        "A PC power supply will be VERY unhappy supplying many amps at 5V and none at 12V."

        Could you string a bunch of 7805s (http://www.raspberrypi.org/phpBB3/viewtopic.php?f=62&t=14512) off the 12V rail?

        Or now that you can back-power (if I read it correctly) off a USB hub with the new revision... maybe(?)

        1. Stoneshop Silver badge
          FAIL

          Re: Great.. .but better ways to do the power...

          Err, you don't use 7805's if you need to drop 7V at 700mA, you use a step-down converter. But a simple 5V PSU with sufficient capacity will cost about the same as the hardware you need to power half the cluster off a 12V rail.

        2. Pet Peeve
          Boffin

          Re: Great.. .but better ways to do the power...

          You could do that, the 7805 is a really nice chip. You'd need to wire up a bunch of them and screw them to a heatsink though. It's less work to use a powered USB hub, which would at least let a bunch of pies share the same wallwart.

          What a mess of power cables! With my supernatural ability to get myself tangled in cords, I would have had this thing in pieces on the floor in minutes. Seriously, in the days of corded phones I frequently tied myself to my own chair if I got engaged in conversation for a while.

      2. Paddy 1

        Re: Great.. .but better ways to do the power...

        You can get 50A 5V supplies from hong kong for under £30

      3. Stoneshop Silver badge

        Re: Great.. .but better ways to do the power...

        A PC power supply will be VERY unhappy supplying many amps at 5V and none at 12V

        So far, none of the several dozen PSU's I've mistreated that way have refused to work. The only thing that will actually happen is that the voltage on the unloaded buses will rise a bit (the 5V output is the one used for regulation feedback) and this *may* cause some overvoltage limiter to kick in and shut the thing down, but this is not something I have encountered even once. It may be true of PSUs meant to power gaming systems with graphics cards that contribute significantly to global warming, run-of-the-mill PSUs can be used without mishap.

    3. Naughtyhorse

      Re: Great.. .but better ways to do the power...

      I do wish people wouldnt say "amperage" its so clumsy

      "sufficient current" will suffice! in both senses.

      </pedantage>

  11. chris 50
    Pint

    Building better worlds

    I would have said they are taking liberties using the term "supercomputer" until I noticed the Lego.

  12. tommitytom
    Thumb Up

    I love...

    ...everything about this!

  13. ukgnome Silver badge
    Pint

    Awesome

    Been into clusters for a while, but this one makes me all fuzzy.

  14. Michael H.F. Wilkinson Silver badge
    Thumb Up

    Lovely idea!

    I think I will show this to my students when next I lecture on parallel computing

    1. James Hughes 1

      Re: Lovely idea!

      And that's the real point - although a cluster (Bramble) of raspi's doesn't have a very good performance figure on cycles per $, compared with a desktop for example, its is VERY cheap as a teaching device for parallel processing.

      If course, if you could access to the GPU, you have 48 processors per Raspi to play with.

  15. Mark Honman

    Got Occam?

    Hmm, if every family member gave me a Pi for Xmas that would be a decent start.

    from the enquiring minds want to know (and are presently too lazy to read the blog) dept:

    * can the graphics part of the Pi processor be used as a floating-point vector processor?

    * what is the computation/communication performance ratio?

    * Linpack performance?

    I guess it will all become clear in time...!

  16. Some Beggar

    The IDEs of March.

    Is the Visual Studio plugin the only python IDE that supports debugging parallel doohickeys using MPI?

    Because I'd quite like to knock up something like this but I am terminally allergic to Visual Studio.

    1. Charlie Clark Silver badge

      Re: The IDEs of March.

      I think I-Python (from the SciPy project) has support for MPI and I'm sure other environments do.

      1. Some Beggar

        Re: The IDEs of March.

        Ta!

  17. proto-robbie
    Pirate

    Reconstruction in Lego, please...

    arf arf

    1. Anonymous Coward
      Anonymous Coward

      Re: Reconstruction in Lego, please...

      Lol

    2. Anonymous Coward
      Anonymous Coward

      Re: Reconstruction in Lego, please...

      Don't be daft. It'll be playmobil around here...

  18. Anonymous Coward
    Anonymous Coward

    Danger?

    "It's not in danger of threatening IBM's Sequoia beast..."

    As if Sequoia will hunt you down if you do over take it.

  19. Mad Hobbit

    Graphics

    I wonder how good these would be for ray-tracing/CGI? Have seen other articles on using a bunch of MBs to make a "supercomputer" that is the backbone for home CGI work.the articles claimed about a 15X speed up due to sending out the frames to all the cpus at once.

    Maybe the Professor could get with the graphic arts dept and run a few benchmarks

    It is really a good project. well done.

    1. Frumious Bandersnatch Silver badge

      Re: Graphics

      Probably not very good. Ray tracing tends to exercise the I/O an awful lot so even if you assign one pi to a particular section of the screen it'll still end up accessing other parts of the scene in a pretty random access pattern (rays bounce). With only a 100MBit connection (and the fact that the USB and Ethernet share a bus) it's easy to saturate the available data channels--a problem that only gets worse as you scale up (though working with different net topology and having more control nodes could definitely help, to a degree).

      On the other hand, having the farm render a typical fractal image would be a perfect application for it since each screen section is typically independent of each other one.

      Despite how impractical this thing is, I'd still love to have one. I'm sure it's also a great teaching resource in spite of (nay, even because of) its shortcomings, necessity being the mother of invention and all that.

  20. Martin Maloney
    Coat

    Why do I always have to be the one?

    Q: What do you say to someone who is trying to steal your Raspberry Pi cluster?

    A: Lego!

  21. Kubla Cant Silver badge
    Go

    If you don't know what to do...

    ... here's what looks like an interesting course on the Cambridge Computing Labs site.

    I intend to work through it as soon as I have (a) a Raspberry Pi and (b) a lot more free time.

  22. James 36
    Thumb Up

    title

    love this, seems like a cost effective way to get to get people into programming for HPC,

    which cannot be a bad thing

  23. Andus McCoatover
    Windows

    As usual, I'm missing something on the PSU front...

    ..Or am I? It's a piece of piss to downconvert 220 volts down to 5V with a switch-mode PSU. Jesus H. Wept, I did it a quarter of a century ago, when I was in my ealy 20's. About 90% efficiency, and I used an optical coupler for the feedback, and a 555 timer to fire the input transistors....(Fed by a humongous resistor, an effing big zener diode, and a bag of capacitors I could barely afford (low ESR)

    Bloody wound the (toroidal) transformer myself. IIRC, I used a strip of copper, covered with sellotape for insulation, wrapped around the toroid, about 10 turns, to get the secondary output working....

    OK, a few explosions on the prototypes, but.... My University Professor would have wet himself laughing, except...I never went to University...Self-taught from having no girlfriend worth mentioning, so living in my mom's house.....Nothing else to do....

  24. Anthony Gamble

    Technical Manager

    The world's first Raspberry bush!

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