How Precision Time Protocol is being deployed at Meta

I remember Google doing this many years ago, does anyone recall the papers that describes distributed storage systems that benefit from highly accurate clocks? Was it spanner or the next generation version of it? I can't remember. I recall finding it fascinating but out or reach since I think they were putting hardware based atomic clocks on their systems, sounded super proprietary.

Yeah, Spanner and the Truetime API. Would be interesting to know whether there are many differences between the implementations (or indeed the abstractions offered). I always wonder whether there are rare occasions where such systems fail (e.g. the bounds reported don't actually capture the true time due to some bug), and what the resulting implications are for systems built on top of them.