> 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.

I can’t go into details about current cases with my current employer, unfortunately. Ultimately, the requirements go through legal and are subject to back and forth with representatives of the government(s) in question. As I said, the problem isn’t passing an audit, it’s getting the initial approval to implement the solution by demonstrating how the requirement will be satisfied. Also, cloud companies are in the same boat, and aren’t certified for use as a result.

This is the extreme end of when you need to be able to say “x definitely happened” or “y definitely didn’t happen” It’s still a “log” from the applications perspective, but really more of a transactional record that has legal weight. And because you can’t lose it, you can’t send it out the “logging” pipe (which for performance is going to sit in a memory buffer for a bit, a local disk buffer for longer, and then get replicated somewhere central), you send it out a transactional pipe and wait for the ack.

Having a gov tell us “this audit log must survive a dc fire” is a bit unusual, but dealing with the general requirement “we need this data to survive a dc fire”, is just another Tuesday. An audit log is nothing special if you are thinking of it as “data”.

You’re a reliability engineer, have you never been asked to ensure data cannot be lost in the event of a catastrophe? Do you agree that this requires synchronous external replication?

> have you never been asked to ensure data cannot be lost in the event of a catastrophe? Do you agree that this requires synchronous external replication?

I have been asked this, yes. But when I tell them what the cost would be to implement synchronous replication in terms of resources, performance, and availability, they usually change their minds and decide not to go that route.