To increase reliability I was equipping a file server with a second system hard drive, and the hardware RAID controller wouldn’t let me create a mirror setup without losing the data on the drives. So I chose to use (Linux) software RAID instead, which I am familiar with and which worked well for me in the past.
I couldn’t get the beast to start up for quite a while. The drive order was juggled around during boot, and the box, being proper server hardware, needed ages to boot up, making trial and error even less fun. I always put off grokking UEFI into the future and wanted to kick myself more than once for it, but damn isn’t it boring.
Well now I finally got around to it, and what can I say.
Read this article from 2014 on how UEFI is supposed to work. It is very good. I wish I had read it much sooner.