Linux Software RAID 10 seems pretty good. Not sure what magic makes it work but I can even remove /dev/sda and it boots fine. Perhaps grub installed on every drive? Hmmm.
@adamd did you find any "official" or at least concise documentation of RAID?
I'm afraid of it to be honest. Badly configured raid means you lose everything on a single drive failure.
@_vasilis_ Hmm. I found some documentation but mostly a lot of experimenting. Pulling drives, recovery, reboot, adding drives, hot spare, etc. It seems pretty good. Lots of reading.
"I appreciate SDF but it's a general-purpose server and the name doesn't make it obvious that it's about art." - Eugen Rochko