You’ll always get back what you wrote even if it wasn’t written durably. It’s kind of how that works. With consensus you make the following kind of argument: 1

You’ll always get back what you wrote even if it wasn’t written durably. It’s kind of how that works. With consensus you make the following kind of argument: 1. The kind of drives you’re using if you’re running a distributed consensus in production is going to be enterprise where these kind of games are played a lot less 2. Establishing consensus is time consuming - by the time peers ack it, you will have flushed to disk. In a common 3 replica scenario, that means 1/3 nodes is taken care of. 3. The probability of 2 disks failing simultaneously in ways that cause a problem is pretty small. But yeah, if your concensus has to be durably written and your flash controller is lying to you, your concensus is worthless (even reading what you wrote isn’t good enough because again - controller can lie to you and satisfy reads from the buffer too)