The Mac Mini situation got worse and worse overnight and today. Constant freezes and hard power downs. I had enough. As a last resort, I wanted to do a clean install of the OS on the Mac Mini. I had to research this, as OS X now comes as a download upgrade, there is no CD or BluRay to install from.
I found a good write-up on Mashable.
I downloaded the Yosemite upgrade from Apple. Then I downloaded and installed DiskMaker X. I had a spare 80 gig USB drive handy. They recommended an 8 gig USB stick, but I wasn't sure I had one that would be bootable, but I knew the little external HDD would work. I let Diskmaker X run and it opened the Yosemite download and created a bootable installable partition on the external HDD.
It took a little time to complete. When it was all done, I rebooted my Mac Mini and when it restarted I held down the Option key. Actually I held down the wrong key and had to shutdown and reboot again. This time it came up with an option of where to boot from, and one of those was my external HDD with Yosemite on it. I selected that, and then it booted and gave me more options. I chose Utilities, then Disk Utility, and then I formatted the hard drive in the Mac Mini. Then I installed Yosemite on it.
The installation went well. It finished, I rebooted. Took a little to configure things. I did not install much software on it. I wanted it as close to pristine as I could get. So I installed the Drobo Dashboard, to get access to my Drobo, and Backblaze went on so I could backup the Drobo. Serve To Me went on so I could serve media out to my iPads. Firefox also, because I cannot like Safari. And that was it.
I loaded up iTunes with all the music and movies on the Drobo, set up home sharing and I was back in business. I went back to binge-watching Breaking Bad. The Mac Mini caused me no problems. I hope it stays that way.