open-source minion supercomputer

It seems like every villian these days has their own plan for world domination. So I thought I’d better get started on my own by developing an open-sourced supercomputer design using the affordable Raspberry Pi 3 computer as the basic building block.

Here, I list some of the pertinent points regarding that design.

Minion Theme

The usual master-and-slaves paradigm for most supercomputer systems is replaced here with a gru-and-minions theme. I intend to add sound events at some point in the future, given the usual “headless computer” arrangement for servers. This should help to flag certain events as they’re happening and add some fun to the project as a whole.

Modular

Each squad of four computers would be contained in such a way that it could connect together with the next set of four.  The name for each squad is E=MC2 which stands for Expandable Minion Cube Cluster.

Self-Contained

Each E=MC2 has its own internal Ethernet switch and a USB charging hub to power things inside. The first in the system also includes a shared USB-based thumbdrive for common resources as well as the code that you wish to run in parallel.

Low-Power

Everything internally is powered with a USB charger so that’s about 15W per computer (or core). The power cost then is less than half the per-core cost of a typical supercomputer for electricity, noting that your average supercomputer must also be cooled.

Low-Cost

Weighing in at less-than-$300, the squad of computers has a per-core cost of less than $75. Throughout, I’m using open-source software. I hope to further minimize costs involved by renting time on a 3D printer locally rather than purchasing one.

Mobile

Since I hope to show this project to others, the entire thing should be relatively mobile by design.

In the “known wi-fi” mode, a single power cable could be the only connection to the device, allowing a laptop to connect to it wirelessly. It would be necessary to first educate the gru node and the laptop with the wi-fi credentials, however.

In the “unknown wi-fi” mode, you would add an Ethernet cable to a laptop computer to connect to the system. It would be necessary to configure the laptop’s Ethernet adapter to match that of the internal wired network.

When the 3D printing work has been completed I envision a clear, self-contained, 6″ cube weighing in a under two pounds (minus the power cord). We’ll see how that plays out soon enough.

Technical Savvy

I’m trying to make this as easy as possible for others to repeat. I’m carefully documenting the hardware list to make this easier to source and so that the same set of 3D printing designs I use might accommodate your own attempt at this.

I do, however, assume that you would have some basic electronics experience, have some tools and a small budget to work with and that you understand your way around Linux terminal commands like ls, cp, mv, mkdir, cd, chmod, chown, sudo, apt-get install as well as how to map a drive on a network in either OS X or Windows, say.

You’d also need to know how git and how github works in order to pull the code and design files.

It will be helpful if you understand DNS, DHCP, the concept of IP addresses and how to configure these on a computer.

Documentation in Real-Time

I’ve purchased the new hardware for this, having done some work already preparing the working image for gru, the master node of the system. I’ve created a repository for everything at e-mc2, noting that there are more than one README.md file within the collection of instructions so far.

As I install the full set of software and dependencies again I will be updating the documentation so that everyone may follow along and be assured that I’ve not glossed over any of the details.

Design Hurdles

I had some problems with the first (several) attempts to power everything with a chassis-based switching power supply but the connections themselves proved to be too problematic. And given the open-sourced nature of the project I would hope that others would build their own so I deemed this attempt “too fussy”. Additionally, the “green” Ethernet switch’s tendency to lower its power demands before any nodes came on then confused this power supply which looked something like this:

  1. The “Green” Ethernet switch would power on and the switching power supply would adjust the input current and output power
  2. The switch would determine that none of the nodes had “linked in” to their Ethernet connections (yet)
  3. The switch then would go into green mode and lower its power consumption and the switching power supply then would attempt to toggle down the output power
  4. The switch and other devices wouldn’t get enough power and then would power cycle, repeating the pattern

This next iteration then changes the power system completely which so far promises to be much easier, resulting in solid connections to the devices.

Common Protocols and Code

I’ve decided to use the Message Passing Interface (MPI) for inter-node communications and the Samba software so that the coder may map a drive to the shared data/code area.

Since I like Node.js, I’ll be developing something so that this is a choice as well. The initial “Hello, Gru!” demo may likely be written in Python, however.

Plastic

I’ve found a local place that rents 3D printers. Hopefully I can get some help designing the files necessary to house all this in a clear cube.

As far as external connections/openings to the cube, there should be one rectangular cutout for the IEC320C5 three-prong power plug and a Keystone receptacle for the Ethernet connector so that it can snap into place. Also, there should be some holes adjacent to an internally-mounted speaker. Optionally, there might be openings on both sides if a fan is added. Overall, it should be a pair of clear plastic parts which snap together to form a cube.

Internally, there should be screw holes and possibly slide rails or bumpers for the Ethernet switch, the USB charging hub and the four Raspberry Pi 3 computers. There should be room for five 1′ Ethernet cables as well as five or six 1′ micro-USB cables for power. As preferences go, it should be relatively easy to open up, remove a computer and its micro-SD card for the sake of maintenance, say.

Although it should operate well without a fan, I’m trying to source a usable 5V-powered fan for the design. Since some of you will want to overclock, this is probably a good idea, I’d guess. That being the case, a cube-to-cube side orientation of venting would create a continous flow of air through all. It may be difficult for everyone to source something like a 5V-to-12V boost module but that’s probably the route to go, combining this then with an inexpensive and readily-available 12V computer fan.

Using the Last USB Port Wisely

The existing design calls for four USB cables to power the computers and a fifth to power the Ethernet switch. That leaves one last USB port to power something. Here are some options.

  1. The existing design utilizes a tiny USB thumbdrive which goes directly into the gru node and is shared by all. Instead, this could be a USB-powered external drive with faster throughput, if so desired. One USB cable would connect the drive to gru and the second would provide power over USB to the charging hub.
  2. A small speaker attached to the grunode should allow sound events to be played in conjunction with code execution. Some speakers are USB-powered and this may be an option.
  3. A USB-powered fan would be the logical choice, however, for the remaining port.

Repository

In case you missed the link above, the repository is now at e-mc2 on github. As of today, it’s probably a bit premature to start your own supercomputer from these designs. I personally would wait until I’ve got more of the MPI-based coding in place and have added the step-by-step instructions for some of the dependencies.

Update 3/27/2017

Things are looking great for the repository and the supercomputer itself. The MPI-based code is now working as well as the website for managing the minions.


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