If you are having data corruption woes, you can also try the old sync; sync; halt method. Shutdown is supposed to run the sync on it's own after killing the non-essential processes. But, you can evoke it at any point.
If I can get into a terminal, I typically run:
sudo sync
sudo sync
sudo shutdown -h now
I was told back in the day, the second sync was there to trigger a head park on old mechanical hard drives. But, as far as I can tell, it just makes "double sure" that the cache is flushed to disk. So far I have not had any trashed SD cards and have rebooted the rig about 2 dozen times, primarily for tuning.
Over the weekend, there was about an hour of power outtage - when it returned all 7 antminers returned to hashing normally but the bitfury did not due to another TOTALLY corrupt SD card (wont format and image - throws 'semaphore timeout 121' errors like the last sd card that became bricked.
off to buy a pair of class 8 cards now see if they handle better.