I remember working in random IT companies, back in the early nineties, where our "servers" were a collection of random desktop machines running Linux.

At the time I think we had one Sun E450, and 20-30 random desktop hosts. All headless, except for keyboards connected. We also had a bunch of phone lines and external modems, which were used to run UUCP jobs overnight, or transfer files other ways, to remote SCO Unixware hosts.

It was only later that I worked with "proper" servers, with niceties such as remote access, redundant power-supplies, and maybe even multiple hard drives (!)