Free Compute Cluster: Part I

It’s been a desire for some time to acquire additional hardware to build a fault-tolerant compute cluster. Around a year ago I scaled back my hardware at home and replaced my Dell R710 with my current host, an OptiPlex 3070 Micro desktop. While that greatly reduced power consumption, I’m starting to reach its limits and would like to try the clustering functionality included with Proxmox.


  • Minimum of 3 nodes, preferably 4
  • I’d like to keep the hardware consistent; each node should be as similar as possible. This prevents me from using the Dell desktops as they’re just too expensive.
  • Small physical size
  • Low power consumption
  • Expandability
    • PCIe slot for an additional network interface
    • Ability to expand RAM is preferable

The regular internet searches for these things led me to thin clients, namely the HP t620 Plus. It appears to be popular for home pfSense deployments because of the expandability and other nice specs not often found in a thin client:

  • AMD GX-420CA (2Ghz quad-core)
  • Two DDR3L-1600 SODIMM slots supporting up to 16GB
  • mSATA SSD slot as well as M.2 SATA
  • PCI Express x4 slot (slot will take x16 physically, just not electrically)
  • Two internal USB ports; might be nice for booting an OS if they weren’t USB 2.0.

Of course, like the famed Model M keyboard, once these somewhat rare gems are discovered and shared online, they become exceedingly rare to find, at least without an excessive hit to the wallet. Poking through eBay, I usually didn’t see units for less than $140, with some selling for over $200.

Today I stumbled upon a lot of 7 units for ~$430. Considering I was only looking for 3 or 4 units, I figured I could offload the rest; as long as I can get $150 each, the extra 3 would more than pay for the other units and maybe even cover the additional parts I’ll need.