I'm curious, do any of the cloud providers offer instances with high-precision clocks? Maybe this is something one of the smaller cloud providers might want to offer to differentiate themselves - instances with GSP clocks.
Edit: Quote from Brewer's post: "Next steps For a significantly deeper dive into the details, see the white paper also released today. It covers Spanner, consistency and availability in depth (including new data). It also looks at the role played by Google’s TrueTime system, which provides a globally synchronized clock. We intend to release TrueTime for direct use by Cloud customers in the future."
Essentially that's what Google's doing by selling Spanner, but you don't get access to the clocks directly. I'd guess that as they get more experience selling Spanner, and they bring the price of the hardware down, they'll rent those directly too.
That's a great question.
Could be a little tricky with AWS for example. It's typical to run a database on a VPC (virtual private cloud), since that layer of the stack doesn't need to be exposed to the Internet. Unfortunately, that means the servers in the VPC can't get to the ⁎.amazon.pool.ntp.org servers.
Skimming around, I don't see any of the cloud providers, VPS providers, or dedicated hosting companies offering anything special, like a local stratum 1 time source for each region/location.
In addition to being extremely precise, TrueTime is explicit about error in its measurements.
In other words, a call to TrueTime returns a lower and upper bound for the current time, which is important for systems like Spanner or CockroachDB when operations must be linearized.
In effect, Spanner sleeps on each operation for a duration of [latest_upper_bound - current_lower_bound] to ensure that operations are strictly ordered.
Your suggestion might improve typical clock synchronization, but still leaves defining the critical offset threshold to the operator, and importantly leaves little choice for software like CockroachDB other than to crash when it detects that the invariant is violated.