Is optical fibers used for distributed systems?
The communication between machines seems to be a bottleneck for distributed systems. Why aren't optical fibers used then? Fiber has been used for over twenty years to connect storage systems to compute resources. Recently, Ethernet over fiber is becoming more common. As @talidayo points out, the fiber connections are unlikely to be saturated. What hurts distributed systems is the overhead of message sending, the packing and unpacking of transmission data structures. As a rudimentary rule, individual nodes / services should spend only a small fraction of the resources and time for marshaling data and the rest on useful computation. In my experience latency is more of a problem than throughput, but then again, totally depends on the kind of application you're building. Network switching can become a bottleneck of it's own, especially once you reach fiber-scale. It's generally better to avoid fiber if you can these days, especially since there are fleetingly few applications that will saturate a modern fiber optic connection.