There are three pillars to the software-defined data centre (SDDC): software-defined compute, software-defined storage, and software-defined networking. Without any one of these three, the whole edifice of the data centre falls down. We build all three to be resilient, “designed for failure,” and robust. Each can be built and rebuilt from scripts that are stored in distributed version control systems. But at the bottom of every application stack in our SDDC, there is a database or file store that cannot—by definition—be re-created from scripts. This is the core data that we mine and make profit from. What happens if (or when) the edifice collapses? How is that core data protected, and is traditional backup up to the task?
There are few fundamental rules to backup, but the one everyone has agreed on for the last thirty years is the “rule of threes.” Three copies of the data: online, offline, and offsite. Without the first, we have no working system. Without the second, errors can creep into our copies, rendering them useless. As nice as instant snapshots are, corruption of uncopied blocks renders all snapshots based off that block useless. Modern Trojans use encryption to keep our data from us in an attempt at blackmail. Finally, offsite protects us from the catastrophic physical failures: fire, theft, and flood.