Raspberry Pi As An ARMed Commodity

“A design goal for BitScope Blade was to enable Raspberry Pi to be conveniently mounted to build compute clusters, cloud hosting platforms and even render or software build farms.BitScope Blade Pack 20, a Quattro Pi based cluster with Power & Mounting for Raspberry Pi.Since the release of the BCM2836 based Raspberry Pi Version 2 it has evolved to become a powerful single board computer.When teamed up with BitScope Blade it makes the ideal candidate as a node in a compute cluster.BitScope Blade solves the key power problem by providing high current voltage regulation right next to the Raspberry Pi.”
 
See BitScope Blade Power & Mounting Solutions for Raspberry Pi
Raspberry Pi is a cheap and widely available DIYer or teaching ARMed single board computer. As such it has sold millions of units but is limited by RAM/computing power/networking. A partial solution to these limitations are boards which mount multiple Raspberry Pi as a cluster. BitScope even has 40-card units available. That’s serious computing power for a lot less money than some more conventional solutions.

The 40-Rpi job costs $745.95 + 40X$35. This gives 10/100 Ethernet, 40gB RAM and 192 gHz-cores of computing power. That would be capable of a lot but would be a dog to configure in the usual way a desktop/server is configured. I would not be happy with the limited bandwidth of networking and storage bottle-neck (USB2). Most likely this would be useful for particularly narrowly defined computing tasks rather than general-purpose computing.

For example, one could distribute files/images of a static webpage over multiple servers and have them aggregated by a 10/100 to 1000mbit/s networking switch. Then it could serve nearly 40gB of stuff from RAM to gigabit/s LAN pretty swiftly. Similarly one could slice and dice a database to multiple devices to get parallelism but it wouldn’t help much if the database would not fit in RAM because the networking is so slow. It could likely encode video frames fairly nicely again accepting a low limit on throughput compared to better hardware. It would definitely expose a student or class to some ideas about networking and distributed computing.

I wonder if it would work with Odroid-C2s, a better unit because of gigabit/s Ethernet, double the RAM and a few more gHz? Then there’s the Odroid-XU4(USB3, 2gB, 1000mbits/s, 8 cores) which is much more powerful and definitely not compatible. Heck, I could still screw them down to a sheet of plywood… Hmmm… I think that works. 4 would do but I could use 6-8 to make Beast IV… It’s good to have options.

About Robert Pogson

I am a retired teacher in Canada. I taught in the subject areas where I have worked for almost forty years: maths, physics, chemistry and computers. I love hunting, fishing, picking berries and mushrooms, too.
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31 Responses to Raspberry Pi As An ARMed Commodity

  1. oiaohm says:

    Deaf Spy x86 has a microcode engine design this comes with unpredictability when you having to perform real-time tasks.

    Every CPU design has it weakness just happens x86 weakness happens to be performing mathematically certifiable real-time processing. The arm chip in the raspberry 3 happens to be able to provide that.

    Sorry I understand real-time limitations and the means for a cpu time to process instructions to change by a wild value due to a microcode update makes x86 totally not suitable to a real-time task.

    Basically about time you stop being insulting and in fact do some homework on the topic before answering.

  2. Deaf Spy says:

    Its a bit scope and problem is in Ohm. Its a mircowaves set up. I understand microwaves. Fifi is an idiot, because he disrupts microwaves. Microwaves have defect in the name. Fifi thinks his tinfoil cap helps against microwaves. Fifi is an idiot, the tinfoil has a defect, too. Cap has a defect, too. Caps don’t pass necessary Audit for security. Real-time microwaves penetrate tinfoil and Fifi is a blabbering idiot.

    There is a point here. Very interesting. Microwaves are switched to real-time. x86 cannot do that. Need ARM for efficient tinfoil cap. Of course, Fifi doesn’t understand real-time protection because he is an idiot and should be using x86 to build a tinfoil cap. This is what everyone in Australia and Canada do. Especially the law in Australia mandates x86 caps. US law mandates ARM caps, this is crap design.

  3. oiaohm says:

    Its a bit scope and problem is in the last half of the name. Its a signal analyser set up.

    Forget Xeon or Atom neither is able to perform real-time dependably its all due to SMM System management mode performing operations in background so disturbing the real-time .

    ram even Xeon Phi is not a real time stable. There are a few thing that different arm and other non x86 chips are in fact good at that x86 are bad at. Building a scope with high quality forget x86. Power, Arm and Mips is what is found your high quality digital scopes.

    So for what that box is built for its fairly good.

  4. ram says:

    Deaf Spy said: “Raspberry Pi is not that cheap. Add power, storage, a box, and for the total you can get an Atom fanless PC that does more and runs everything.”

    He has got a point there. Plus one can get a heap of Atom cores on a single board, in fact you can get alot of them on a single chip!

    http://www.intel.com/content/www/us/en/processors/xeon/xeon-phi-detail.html

    72 cores, 288 threads, now that is some GRUNT!

  5. Deaf Spy says:

    Varnish stores data in virtual memory and leaves the task of deciding what is stored in memory and what gets paged out to disk to the operating system.

    Varnish is heavily threaded, with each client connection being handled by a separate worker thread. When the configured limit on the number of active worker threads is reached, incoming connections are placed in an overflow queue; when this queue reaches its configured limit incoming connections will be rejected.

    This is broken by design. On several levels.

    You don’t dedicate a separate worker thread for every client in an IO scenario. That leads to too many threads, wasting memory and CPU cycles due to intensive scheduling and context switching.
    You don’t delegate your memory management to the OS when you want to scale high. OS-based memory (de)allocations are expensive. You need to pool your objects and reuse your memory.
    Doing both means you end up with threads waiting on IO operations and page faults.

    Good design evolves around having a thread pool, and involves techniques like epoll, kqueue, or IO completion ports.

    No wonder this miracle is used by mostly open websites. Everyone with serious requirements knows better how to cache his static content.

  6. Deaf Spy says:

    I think Kurkosdr does not understand schools.

    I don’t know about Kurks, but you don’t understand modern IT for sure, Robert.

    Raspberry Pi is not that cheap. Add power, storage, a box, and for the total you can get an Atom fanless PC that does more and runs everything.

    Raspberry Pi is good for teaching robotics and IoT, and there are even cheaper alternatives to it.

    I have tried Raspberry Pi as a desktop – not good at all, even browsing is a pain. But great to measure the temperature of your beer, and upload all data to a cloud storage.

  7. dougman says:

    As much as thei POS costs, I could build me another UNRAID server. Using an Intel board and processor.

  8. DrLoser wrote, ” In 2016, if you please: static web pages are a thing of the past.”

    That’s not true. This blog, for instance, is dynamically generated but most of the content is delivered from a cache as constant data.

  9. DrLoser wrote, “You have, of course, purchased a Raspberry Pi, Robert?”

    Not yet. I have an Odroid-C2, which is a similar animal but with a few better characteristics which helped me decide: RAM/CPU/gigabit/s NIC.

  10. dougman says:

    “I’ve been in schools with hundreds of students with the entire IT budget being ~$2K”

    Did the Inuit huts have electricity? I bet that was back in the late 80s, not today in the the early part of the 21st century. For example, say 300 students have an Apple iPhone, that’s $180K in IT right there.

  11. Kurkosdr wrote, “Load Drupal on it or some other slow CMS and set up a “web server” with the worst bang-for-buck-ratio on the planet. Then give a lecture titled “the wrong tool for the job”.”

    I think Kurkosdr does not understand schools. I’ve been in schools with hundreds of students with the entire IT budget being ~$2K and “maybe we can cover repairs from petty cash”. There often isn’t money to dedicate to a proper server for teaching. So, if you have a bunch of general-purpose boxes which are very cheap and you can lash them together into a network and configure them to do what you want, you are in Heaven without having first having to die. You don’t want students playing with the Administrations database holding payroll, correspondence, databases, reports, etc. That will likely be in the office and perhaps not even on the LAN used by students.

    So, for teaching, you want something that works, first, and you don’t care that much about throughput or longterm reliability. It’s a bonus that you can actually have students lay hands on it, configure it and play with it. That’s a learning environment. e.g. The legacy PC shipped mostly with TOOS which forbade all kinds of delicious educational opportunities for students like installing multiple copies, networking any old way, and not having to count the damned licences. Consider the legal implications of having students “Accept” the EULA from Hell. Is that legal? They are underage mostly. So, expensive hardware and software is not best for education. That’s the truth. I’ve been there and done that. I got a lot more bang for the buck in my labs using castoff computers and would have loved to use something like the Odroids or Raspberries that are available today.

    If I had a bunch of such nodes and wanted to run Drupal for the kids, it’s pretty easy. MySQL/Mariadb have means to run in clusters so the server is less a bottleneck and we have distributed file-systems too to make the limited bandwidth per node less of a problem. What’s the likely data-rate with 24 kids in the lab, anyway? Nothing says they have to all connect to the same IP address/server/database. Whatever works for the project is what you use. I’ll grant you that some old legacy PC may be a better server than a cluster of Raspberries and they are cheap and plentiful, but if you can only have a very limited budget/space, Raspberries can do. In terms of throughput, they are probably every bit as good as PCs from ~15 years ago. ISTR we got lots done with them.

    One more huge advantage of Raspberries and the like: you can have distributed DC power. You can run a whole lab from a single battery and charger, except for monitors. I’ve been in labs with ~4KW heat dumped into a poorly cooled lab and sweat would drip from my nose even in winter. Raspberries allow labs to be set up in all kinds of places that would not handle two dozen legacy PCs and the Raspberries are quieter, a vital matter when you want students to hear conversation and thoughts.

  12. kurkosdr says:

    BTW, I decided am buying an RPi3. I want a basic browser for my Bravia (by basic browsing I mean Facebook, Twitter, news sites, and the like) and having to use my Nexus Player for this is getting a bit long in the tooth. I cannot even get a proper browser (with adblock) on it just like I do on all my smartphones (Brave browser) or my PC (ublock origin), and using Chrome for Android is getting annoying. Getting a full NUC seems like an overkill and my ODROID U3 is not really well-supported software-wise. At least Raspbian and the mostly open-source VideoCore IV chip look like a safe bet.

    I had rejected the Pi due to its processor which was not good for anything, but Pog gave me the chance to look at the new Pi3, which I had no idea it even existed *hugs and kisses*

  13. Kurkosdr says:

    What “teaching” does it enable, Robert?

    Can I answer the question instead? Here is my attempt: Load Drupal on it or some other slow CMS and set up a “web server” with the worst bang-for-buck-ratio on the planet. Then give a lecture titled “the wrong tool for the job” .

    The benefit of the Pi is having just enough computing power to run a basic desktop (now that the CPU is a proper ARMv8 and not something taken out from an old Symbian phone) in order to offer a basic programming environment and basic browser, so that lots of students can have their own little computer in a classroom. And you can easily reimage those Pis using a card reader. Heck, those students can take their whole computer at home to practice. Then there is the Lego Robotics thing using the GPIO pins, since this thing requires only 4Watts to run.

    But the “server box” in the picture above? You take all the advantages, namely the Pi’s minimal size, ease of transport and GPIO pins and seal them in a box… that would be 746 american dollars please (plus the cost of the Pis), aka 2100 dollars. You could build a rack of i7s or two blades of Xeons or (if you like many cores that much), whatever AMD sells that’s supposed to compete with the i7 and the Xeon. Commodity!

    So, no Pog, this thing would NOT “be useful for particularly narrowly defined computing tasks”, but you are welcome to mention a couple of those particularly narrowly defined computing tasks anyway for our amusement.

    This thing is a neckbeard weekend project taken way too far.

  14. DrLoser says:

    You have, of course, purchased a Raspberry Pi, Robert?

    A cheap way of proving that you have some sort of clue about whatever blather you are presently delivering to the (sadly depleted) Peanut Gallery?

  15. DrLoser says:

    Only a nitwit would do that.

    That’s not quite fair, Deaf Spy. A nitwit would have to find enough static web pages to make this nitwit proposition even worth considering.

    Which it very definitely is not, Robert. First of all, I challenge you to come up with a believable use case for such a proposition. In 2016, if you please: static web pages are a thing of the past.

    But, you say, if such a thing can cope with static web pages, surely it can scale to dynamic web pages?

    Go boil a frog.

    Bwahahahahahahahahaha!

  16. DrLoser says:

    Greater than 600K. Pah.

  17. DrLoser says:

    As a bonus post for anybody who, unlike Robert, is more interested in the firmware/hardware end of teaching … Robert being more interested in pushing useless FLOSS crap that even he wouldn’t be able to find a use for … here is an example of an actual, plausibly pedagogic, cheap, FPGA board that does a better focussed job than the RasPi at a comparable price.

    Or you could just use FPGA simulators in the Cloud. Either one would be a far less dim-witted choice than the one that Robert clearly refuses to make for himself, but as always is prepared to inflict upon countless thousands of school children on the simple grounds that he really doesn’t care about education, but would rather give himself warm fuzzy feelings.

  18. DrLoser says:

    Well, anything that can benefit from having a cheap computer that one can interface to usual peripheral devices and even analogue inputs/outputs to an ADC/DAC, and be programmable.

    No, that won’t do, Robert. Specifics please.

    And those specifics had better make the case that the teacher and pupil wouldn’t be better off with the obvious alternatives. Chromebook amongst them.

  19. DrLoser says:

    A search for “deployment of raspberry pi” finds >600K hits

    It’s hard to find a case with less evidence than this, Robert, even if you are stupid enough to believe in search statistics. (Apparently you are that stupid.)

    Now, here’s a three term random search during the composition of which three terms I tried very, very hard to come under that 600K,/b> limit:

    Furry wombat love: circa 1,450,000 hits.

    Most of them less pornographic than the sort of post that involves a neckbeard pleasuring himself with a tiny defenceless worthless piece of hardware, I would imagine.

    So, here’s a challenge for you. Leave aside M$, because obviously you will be pelted with billions of results. Let’s try something more like Pi.

    Let’s, in fact, try Chromebook. Add two terms to that and see if you can get under your pathetic little 600K barrier.

  20. DrLoser wrote, “What “teaching” does it enable, Robert?”

    Well, anything that can benefit from having a cheap computer that one can interface to usual peripheral devices and even analogue inputs/outputs to an ADC/DAC, and be programmable. Since there is an abundance of GNU/Linux software out there and some platform independent stuff it’s very adaptable. It doesn’t have to perform wonderfully to be useful in classes. It just has to work and it does.

  21. DrLoser wrote, “This nonsense will not scale.”

    1. Facts not in evidence.
    2. Why should a project designed for some small task need to scale?
    3. Who cares? If someone wants to do it it’s their project.
  22. DrLoser says:

    Quoting Dougie:

    All these projects fun, perhaps, but they sure are a huge waste of money.

    A huge waste of money, very possibly. But what Dougie failed to mention (because he is an innocent naïf and clearly believes that you will draw the obvious conclusion that both Dougie and I have drawn) is a slightly different, yet massively more important, thing.

    This nonsense will not scale.

  23. DrLoser says:

    Actually, and I am prepared to wait for your response on Erlang, I can think of one other possible educational niche for the thing: robotics.

    Have you looked at the market for small cheap educational robotics systems, Robert? I haven’t. But I trust you will dig at least one up that praises the RasPi to the high heavens.

  24. DrLoser says:

    Raspberry Pi is a cheap and widely available DIYer or teaching ARMed single board computer.

    Really? What “teaching” does it enable, Robert? (I’ll give you DIY for free.)

    Low-level hardware/firmware skills? Better, I would think, a FPGA system. Certainly more relevant to industry.

    Web skills? I think not.

    Database/server skills? Even you would not claim this.

    Common Office (might even be Libre) skills? A tad underpowered and lacking graphics oomph.

    M$ … let’s not even bother to discuss getting valuable (ie worth dollars in the marketplace) skills via the RasPi.

    Linux, ah, there you have it. Except that you don’t. The RasPi is a total waste of money compared to, say, a bottom-end (and probably hacked, because otherwise you’re not dealing with much in the way of education) Chromebook.

    I do have one small crumb of comfort for you, though. Erlang. Think about it.

  25. Deaf Spy wrote, ” Raspberry PI is a DIYer, and only that. It is not used in actual production environments, because it can’t survive any conditions out of a common room.”

    It’s widely used in schools as a cheap computer with which students can try lots of techniques. A search for “deployment of raspberry pi” finds >600K hits many of which are DIYers, classrooms, various micro-servers and IoT. Folks seem to use it like a hammer or screwdriver instead of a virtual machine somewhere and deploy it wherever it’s needed. If I were going to use Rpi, it would likely be in a greenhouse or growing operation to monitor/control temperature and watering. It could be used to point a solar array too. I could use it to give intelligence to a genset. It is a little too puny for many of my IT tasks like databases, file-storage/sharing, web-servery with PHP and such as well as desktop applications. I would use Odroid-something instead or the promised small server boards.

    Here’s an example of using Rpi to track the sun for increasing production of solar panels. Here’s a larger deployment.

  26. Kurkosdr wrote, “Without some higher education, if your kids don’t have a trust fund or piece of real estate to lean on, they ‘d be yet another broke young person competing with many other broke young persons for the few jobs that haven’t gone to China or Mexico. Add-in the illegal immigrants you call refugees competing with jobs but at much lower rates (because they have their housing covered by the government and your kids don’t), and the future of your kids looks grim.”

    Not to worry. The kids are off to a good start. One has a professional degree. Another is raising a family and hubby is getting his trade-papers. She has college credentials and is very skilled. For keeping fit, she’s performing at ballroom dancing… She’s also a skilled videographer. Another is a computer guru and the goto guy at a big outfit making web pages/databases/applications. Two own their own homes and one drives a Cadillac, just because he can. They are well set for life and TLW and I own a nice chunk of real estate as well as my stock portfolio. Life is good.

    Further, Canada is full of optimism and space to grow unlike that dark brooding cave that USA has become. I think more than half what my kids have that will help them thrive comes from merely being Canadian. Immigration is just the icing on the cake, ensuring continued economic growth for years to come. Meanwhile, USA is a tree busily pruning its roots as a big storm approaches. USA is headed to catastrophe of its own making. On a lighter note, I see that rich immigrants are still coming to Canada because it’s a great place to live.

  27. ram says:

    That cluster is an interesting device. Thanks for pointing it out.

  28. kurkosdr says:

    You can’t take it with you and the kids would likely waste it anyway…

    That’s harsh. Without some higher education, if your kids don’t have a trust fund or piece of real estate to lean on, they ‘d be yet another broke young person competing with many other broke young persons for the few jobs that haven’t gone to China or Mexico. Add-in the illegal immigrants you call refugees competing with jobs but at much lower rates (because they have their housing covered by the government and your kids don’t), and the future of your kids looks grim.

    I for once am glad my parents paid for my higher education and will leave to me a piece of real estate I can lean on (or at least stay in) and possibly some cash. Guess I am lucky, considering many parents are like Pog, aka spend it all on cheap tractors and silly one-seater EVs, and the kids can go screw themselves.

    Hope you have at least arranged your funeral expenses Pog, because your kids may not be able to afford that, and with debt already being such a tight noose around the neck of many young people, they might go for the “have some friend say some goodbye words and dig a deep-enough hole” option. Also, if your brain stops working, your kids will have to arrange for a nurse to take care of you. Even if you have the cash, you won’t be able to arrange it yourself, your kids will have to. Which they might not have time to do if they already have too many survival problems of their own and have to work two jobs as minimum wage workers. So, better start taking care of your kids more…

  29. Deaf Spy says:

    For example, one could distribute files/images of a static webpage over multiple servers and have them aggregated by a 10/100 to 1000mbit/s networking switch.

    Only a nitwit would do that.

    Raspberry Pi is a cheap and widely available DIYer

    You got this right. Raspberry PI is a DIYer, and only that. It is not used in actual production environments, because it can’t survive any conditions out of a common room.

    It is nice to see how people are experimenting, though. But one should be well aware that these are only experiments bearing tags like “Don’t do this at home”, “No support” and “Not for production environment”.

  30. dougman wrote, “Are these projects fun, perhaps, but they sure are a huge waste of money.”

    There’s this about being old and having money. You can’t take it with you and the kids would likely waste it anyway… All of my projects so far have born fruit except the inverters and the alternator. That should change soon. I’ve found my hacksaw so I can resume cutting steel for the cart and put things in place before they too disappear. TLW moved my snowfence around. If the snowmobiler goes around that she will declare war… Life is interesting even if I’m getting really old.

    According to much learned advice, if you don’t use it you lose it so all this planning is supposed to keep my brain ticking over. I just got off the phone with a young man taking electronics as part of his journeyman course and I was able to rattle off solutions in my head to simple transistor circuits, just as I did 50 years ago. I think the brain still works.

  31. dougman says:

    LOL..waste of money, silly and downright useless.

    It reminds me of a fellow I know, that makes high-power 48Vdc converters for electric golf carts that are water cooled and can handle a few thousands amps. They are neat and fun to a degree, but old men in Florida are willing to pay a butt-load of money, to have bragging rights on whose golf-cart is faster.

    Another fellow I know, spent $10K on a custom lawn-tractor that he runs at the tractor pulls. Custom two-stroke engine running at about 10K rpm, and unknown torque. All I know he wins every time.

    Are these projects fun, perhaps, but they sure are a huge waste of money.

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