> It matters to me, because I don’t want to be dependent on a sync ack between two fault domains for 99.999% of my logs. I only care about this when the regulator says I must.

If you want synchronous replication across fault domains for a specific subset of logs, that’s your choice. My point is that treating them this way doesn’t make them not logs. They’re still logs.

I feel like we’re largely in violent agreement, other than whether you actually need to do this. I suspect you’re overengineering to meet an overly stringent interpretation of a requirement. Which regimes, specifically, dictated that you must have synchronous replication across fault domains, and for which set of data? As an attorney as well as a reliability engineer, I would love to see the details. As far as I know, no one - no one - has ever been held to account by a regulator for losing covered data due to a catastrophe outside their control, as long as they took reasonable measures to maintain compliance. RPO=0, in my experience, has never been a requirement with strict liability regardless of disaster scenario.