I acquired a mid-2011 Mac Mini Server. It's got two 500 gig hard drives in it, and 8 gig RAM. Running OS X Lion Server. The guy who sold it had started using it as a server, but never really got into web development. So he was using it for his photos and music. Then he needed money, so he sold it.
He had deleted most of his files, and he had erased most things, but left his Apple ID and other things behind. I didn't care, I wanted a clean start and wanted to erase everything. First I tried to install Mavericks, thinking that would erase Lion Server. Twice, it got about 4 gig into the 5.32 gig download and then stopped and told me it couldn't do it. I wasn't sure if this was because of download problems, or if it was a permissions problem with conflicts over Apple IDs.
Next, I hooked up an external DVD drive, and tried to install a non-server version of Lion. It told me it wasn't allowed to do that on this machine.
Then I did some research. Turns out there is a hidden partition on the hard disk. Reboot with holding down Command-R gave me a special menu. First up, I used the Disk Utility to erase the two hard disks. Then I asked it to reinstall Lion. Turns out it reinstalled Lion Server. But it downloaded more stuff for six hours, and finally it finished and it reinstalled Lion. This time, I got my Apple ID in, and it was the only Apple ID it knew about. Then into the App Store and start the free upgrade to Mavericks. This was the 5.32 gig download again. It got all the way to 5.20 gig downloaded, and then it froze. Ten minutes went by, then fifteen, then it rushed ahead and downloaded the last little bit.
I then got told that the Server components had been disabled. If I wanted them, I could go into the App Store and buy the latest version. I was happy with that. I don't want the server component. The Dock icon for Server now had a large X through it. I put it in Trash. Then I used Finder and put the whole Server app into Trash.
This is great. I just wanted another newish Mac Mini that will take Mavericks, and hence XCode, so I can do some development, and that's what I ended up with. I'll get XCode on it next week, and the 8 gig RAM will be a big help there. I'll take the other one home and use it for the same thing. So now, Anne has a newish Mac Mini with Mavericks, and I now have two of them. We can probably stay up-to-date with new versions of the OS for another five or six years.