Of course, you can do this in good conditions. The extremely powerful part that TrueTime brings is how the system degrades when something goes wrong.
If everyone is synced to +/- 20ns, that's great. Then when someone flies over your datacenter with an GPS jammer (purposeful or accidental), this needs to not be a bad day where suddenly database transactions happen out of order, or you have an outage.
The other benefit of building in this uncertainty to the underlying software design is you don't have to have your entire infrastructure on the same hardware stack. If you have one datacenter that's 20yrs old, has no GPS infrastructure, and operates purely on NTP - this can still run the same software, just much more slowly. You might even keep some of this around for testing - and now you have ongoing data showing what will happen to your distributed system if GPS were to go away in a chunk of the world for some sustained period of time.
And in a brighter future, if we're able to synchronize everyone's clocks to +/- 1ns, the intervals just get smaller and we see improved performance without having to rethink the entire design.
> Then when someone flies over your datacenter with an GPS jammer (purposeful or accidental), this needs to not be a bad day where suddenly database transactions happen out of order, or you have an outage.
Most NTP/PTP appliances have internal clocks that are OCXO or rubidium that have holdover (even for several days).
If time is that important to you then you'll have them, plus perhaps some fibre connections to other sites that are hopefully out of range of the jamming.
> fibre connections to other sites that are hopefully out of range of the jamming.
I guess it's not inconceivable that eventually there's a global clock network using a White-Rabbit-like protocol over dedicated fibre. But if you have to worry about GPS jamming you probably have to worry about undersea cable cutting too.
If everyone is synced to +/- 20ns, that's great. Then when someone flies over your datacenter with an GPS jammer (purposeful or accidental), this needs to not be a bad day where suddenly database transactions happen out of order, or you have an outage.
The other benefit of building in this uncertainty to the underlying software design is you don't have to have your entire infrastructure on the same hardware stack. If you have one datacenter that's 20yrs old, has no GPS infrastructure, and operates purely on NTP - this can still run the same software, just much more slowly. You might even keep some of this around for testing - and now you have ongoing data showing what will happen to your distributed system if GPS were to go away in a chunk of the world for some sustained period of time.
And in a brighter future, if we're able to synchronize everyone's clocks to +/- 1ns, the intervals just get smaller and we see improved performance without having to rethink the entire design.