I’m a little confused with what’s going on in this thread. There’s an implication here that Redis is somehow different than using ETS tables, but there is no reason you can’t just put an ETS table on one node and use it exactly like you would use Redis! You would have no fault tolerance and higher latency, just like Redis. The only reason you would want to actually use Redis is if you wanted its vast array of fancy data structures, which in this case maybe you don’t, seeing as you have already implemented your system on ETS.
Again, it’s perfectly valid to use Redis for its functionality, but “ETS and GenServers” were absolutely designed to be used “cross-node”. OTP literally could not be more designed for that! It’s, like, the entire thing!
This is not a literal answer, but the quintessential example would be something like an exchange/order-matching system: something which processes (financial) transactions. If you want to learn more about that the magic keywords are “LMAX architecture”, plus check out Tigerbeetle for a modern fault-tolerant rendition.
Apologies in advance for nitpicking something you’re probably fully aware of, but CAP and “centralized/distributed” are separate concepts. You can have a distributed consistent system, and you can also have a single-threaded inconsistent system, though this is less common because in a single-threaded system consistency is so easy to achieve.
