dev-ops is a profession/activity which, bottom line, means: automate the configuration of the software you need. There are world-famous tools like Ansible which are designed precisely for this activity. If you write a very detailed Ansible recipe (a set of instructions for Ansible) you can automate (sometimes 100% automated) the setup of a computer/server. Ex.: imagine you want to create several validation nodes: you can write a detailed recipe which is capable to spin up a virtual machine in seconds or minutes
redundancy: it's a principle coming from old-school engineering vastly applied in aeronautics, for instance. It means: let's duplicate a mechanism so that if it breaks there is another mechanism in place that can substitute the broken one in real time so that the system, as a whole, won't be affected by the breakdown.
Fortunately, when it comes to nodes, you don't need old-school redundancy because redundancy is already embedded in the concept of decentralization. Your node will be just an atom of a much bigger worldwide system. If your node goes down, the entire system won't be affected. That's the beauty of decentralization.