There’s just something about the low price of a Raspberry Pi that compels people to buy them by the handful. The next logical step, of course, is to link your Pis together into a poor man’s supercomputer. To showcase his 6-Pi, Kim Sung-Taek created a custom enclosure out of acrylic with enough room to fit his six Raspberry Pis, a USB power supply, and an 8-port network switch.
This cluster runs Apache Spark/Hadoop in cluster mode and has been stable so far, according to Kim. His only complaint is that the 30cm USB cables stick out further than he’d like. A commenter on his blog later pointed him to some 15cm cables that might tidy things up.
While a 6-Pi cluster is nothing to sneeze at, we have seen clusters up to 40 and even 120 Raspberry Pis. That said, at $40 each (for the Raspberry Pi Model 2) a cluster of 6 seems a relatively reasonable expense for those looking to dabble in supercomputing.