Well after I upgraded from 6.0rc2 to 6.0rc4 my drive 1 showed bad and had some issues with other drives. I had shut the server down completely and did a "Cold boot" and drive 1 showed as bad.
I start the drive set and it still shows drive 1 bad. I stop it and it shows drives 1-8 missing. I had no issues with rc-2. Previous version "beta version" I had to run in xen mode in order for this to go away.
here is the sys log.
https://lilnetwork.com/download/nas/6-8-2015.log