@futurebird Yes, most large datacenters have I'm sure many metric shittons of ethernet cables in them. Usually a lot of work goes into cable management, otherwise things
would be totally out of control.
There are companies that have even designed large compute clusters in clever ways to minimize cable length, which minimizes latency and saves money and effort in wiring.
There's often a fair bit of fiber optic cables too, but there's tradeoffs in terms of cost. Also, it takes an incredibly beefy server to be able to make much use of the very high bandwidths that fiber optics provide, so sometimes application servers are copper to switches, which aggregate multiple servers together into one very high bandwidth fiber optic backbone link.