At 2003 (before cloud and virtualization), many companies used to: Have the servers in-house. The servers usually are PCs with/without steroids. And usually don’t follow any standards. In this photos, we can see: BEFORE: The servers are the floor or one over another. AFTER: We have created 02 new racks to host the new servers and old too.

A Linux’s server infrastructure diagram from 2003. Yeah, that is an SVG and it was a bit complicated to make changes, for luck, at this time without cloud and only a few virtualization servers, the infrastructure didn’t change so much.