A similar question exist which the author himself has answered by actually giving in on the question and it relates to Windows 8. I found an answer but it is for Windows 2016 Server which might be different.
I have created a mirror on Windows 2016 Server running as a VM (Oracle Virtual Box).
To test it I replaced one of my virtual disk with a new one after power down. After boot I have strangely 3 disks in concern.
One disk from the mirror. Disk 1 status: Failed Redundancy, online
The new unformatted disk which is supposed to be part of the mirror. Disk 2 dynamic status : online
A missing disk
I tried to select the missing disk an choose "Resynchronize mirror" Nothing happened, then I tried "Reactivate volume" and I got "plex is missing"
What is plex and how do I rebuild my mirror?