<p>As tests on Rock PI-X <a href="https://www.mouton.in/blog/20210112_minicluster_testingrockpix/" title="Testing Rock PI-X for cluster node">were successful</a>, I ordered five other units. The Rock PIs come from China and even if shipping usually takes more than two weeks, it is more than time to prepare provisioning tools.</p>

<p>Before buying all the nodes of the cluster, it is worth testing a unit. The short list of candidates was quickly drawn:</p>

<p>Chinese manufacturers offer a large choice of low-cost, fanless, servers. I chose one with more than enough power and four Ethernet plugs. Only two RJ45 connectors were needed but additional ones allow me to split the cluster in two sub-nodes and test consequences of inter-networks communication. For example, a kubernete-to-kubernetes cluster connection might be tested.</p>

<p>Directly powering all components would require to plug 6 (cluster nodes) + 1 (cluster server) + 1 (switch) = 8 wires! Added to the cable mess it would imply inefficient powering with at least 6 low-cost power adapters.</p>

<p>The structure of the mini cluster should stay simple to ease build and setup. The following hardware architecture should be just enough: <figure><img src="/img/minicluster.png" alt="minicluster hardware architecture" width="434"><figcaption> <h4>minicluster hardware architecture</h4> </figcaption> </figure> </p>