alt Hacker News> 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.