I have a very simple virtual environment at home that I use to learn about new tech, study for certifications, etc. However, my employer maintains labs for each department that can be used for the same, as well as reproducing customer issues. In fact, I manage the lab for my team (30+ people). We were just given a budget to purchase a pair of server as well as purchase upgrades for a few others. As of right now we have 7 servers, a full blade chassis, enterprise grade SAN, and a half dozen client devices, And that is just one rack of 40 that my business unit maintains at just my site. There is also a training lab that is physically separate (although it isn't as well equipped).

Linux