My troubleshooting ability in Linux is not impressive, just so you know. I can follow instructions very well on the other hand. I have a Linux server with Linux raid. It was working well with no problems for about half a year but then I had a power failure and have been getting the same problem ever since. After rebuilding the raid all my files are still there, so that's a good thing. When I reboot the server the raid device md0 is gone.

 pi@pinas:~ $ cat /proc/mdstat 
 Personalities : 
 unused devices: <none>
 
 pi@pinas:~ $ ls /dev/md*
 pi@pinas:~ $ 

I found an [issue here][1] that seems to have helped other people but I tried it and it did not help. I also looked at several other sites all saying the similar things. I use webmin to create the raid and the mdadm.conf "looks" ok. I don't know if I am searching the internet for the right things or even if I am looking in the right log files. Does anyone have any ideas?

Thanks in adavance.

***Edit 1

 root@pinas:/home/pi# service mdadm start
 Failed to start mdadm.service: Unit mdadm.service is masked.

I am wondering if the mdadm service is even running. The process is not currently active on the system and I have no idea how to tell if it is configured to start on boot, how to start it or configure it to start on boot.

***Edit 2

 systemctl list-unit-files
 [email protected] static 
 [email protected] static 
 mdadm-waitidle.service masked 
 mdadm.service masked 
 [email protected] static 
 mdmonitor.service static 

I found this. I don't know exactly if this is bad but it is suspicious looking. Is this how it should be? None of them say enabled and I would think they should. Any Ideas?


***Edit 3

 systemctl list-unit-files
 [email protected] static 
 [email protected] static 
 mdadm-waitidle.service masked 
 mdadm.service masked 
 [email protected] static 
 mdmonitor.service static 

 dpkg-reconfigure mdadm
 update-initramfs: deferring update (trigger activated)
 update-rc.d: warning: start and stop actions are no longer supported; falling back to defaults
 update-rc.d: warning: start and stop actions are no longer supported; falling back to defaults
 Processing triggers for initramfs-tools (0.120+deb8u3) ...

I ran the commands that @telcoM suggested and this is the output. I also tried doing a reinstall then those commands, but still the output is the same.

 [1]: https://ubuntuforums.org/showthread.php?t=1223457%22issue%20here%22