Paul Brown's 1U Server Build Crams Five Raspberry Pis Into Low-Cost Colocation Facilities

Developer Paul Brown has been working on a project to take advantage of cheap colocation in data centres — cramming Raspberry Pi single-board computers into a 1U chassis while keeping under the 1A/120V power limit.

"There are server colocation providers that allow hosting a 1U server for as low as $30/month," Brown explains, "but there's a catch: There are restrictions on power usage (1A @ 120v max, for example) because they're expecting small and power-efficient network equipment like firewalls."

Brown wasn't looking to host network appliances, though, but as much compute as possible — which is why he turned to the Raspberry Pi family of single-board computers, and an idea to cram them into a modified 1U server chassis.

The project puts five Raspberry Pi 4 Model B 4GB single-board computers, 1.2TB of SSD storage, a gigabit Ethernet switch, and management hardware — comprised of relay modules that allow one Raspberry Pi to power-cycle the others remotely, and another relay module should the control Raspberry Pi itself need cycling — into an off-the-shelf Supermicro SuperChassis server case.

First, Brown removed the hard drive bays and front panel extension cable; next, the Raspberry Pis were installed in heatsink cases, the SSDs into USB enclosures, and everything taped down inside the case for lack of mounting options. The rear panel is then nibbled out to mount an Ethernet port, and a power supply break-out used to convert the ATX power supply into feeds for the Raspberry Pis.

While Brown's server tops out at five Raspberry Pis, there's space for at least seven in total — and even at five, he points out the cost advantages over similarly-specified cloud services over a long enough time period.

The full write-up, plus a bill of materials and alternative hardware options, has been published to GitHub — along with software configuration instructions for reducing power draw and booting from the SSDs.