Re:The end of a myth: Distributed transactions can scale
by rezonant on Tuesday April 11, 2023 @03:50AM
(#35522124)
Perfect time synchronization over a network with unknown latency is provably impossible.
Fairly certain distributed physics experiments will be using atomic clocks that are not synchronized over the network. And/or they'll use direct satellite or GPS time sources which have predictable latencies.
Re:The end of a myth: Distributed transactions can scale
by t0b1 on Tuesday April 11, 2023 @07:42AM
(#35523686)
CERN at least seems to be using a solution that is running over Ethernet[1] but with custom hardware that is probably fairly expensive. They use a single time source and then measure the delay between each switch/node.
Though, this is limited by needing to be able to run a cable between each node so idk how your definition of a distributed experiment fits.
Re:The end of a myth: Distributed transactions can scale
by sethammons on Tuesday April 11, 2023 @07:18AM
(#35523492)
We've several thousands of nodes in our system. Our ops people have witnessed clock skew from seconds to months that are transient. Time is constantly synced via ntpd.
You can't trust system clocks in a distributed system to ensure ordering. Some reading:
https://codeburst.io/why-shouldnt-you-trust-system-clocks-72...
Most machines will also know it is 8:11.
The question is how much resolution do you need and are your clocks accuratly synced enough for the thing you plan to do.
You are aware that many of the physics experiments that operate at the edge of what is possible use extremely accurate clocks synced over national and sometimes continental borders?
¹ let's ignore the ones that have been configured incorrectly