When I did server room buildouts for VFX, I used to use DAC for short distance and fibre for anything longer than a rack.
However that was mainly because I always thought fibre was much more fragile. I mean in a sense it is, it really doesn't like being pull through a thatch of other wires. The solution of course is to do nice cabling.
Nowadays I'm not actually sure if DACs are cheaper than fibre now
> Nowadays I'm not actually sure if DACs are cheaper than fibre now
Yep still are, although fiber transceivers are surprisingly affordable, and of course you can usually re-use jumpers when you upgrade transceivers so TCO over a couple generations might be comparable.
However that was mainly because I always thought fibre was much more fragile. I mean in a sense it is, it really doesn't like being pull through a thatch of other wires. The solution of course is to do nice cabling.
Nowadays I'm not actually sure if DACs are cheaper than fibre now