I have an external USB 3.0 RAID array that I'm using as JBOD. It's connected to the Mac Mini Server (Late 2012). 10.8.5 kept sleeping the external array, and it steadfastly would not wake up.
I had moved my home directories over to it, and have everything on the Mini (including the external drives) encrypted with FileVault 2.
You can imagine the joy it was to unfrak the system, but Time Machine pulled me through. I had to reformat the boot drive, restore from backup, move my user folders back over to the boot drive, then reset FileVault 2 on the boot drive.
Everything on the Mini now seems back to normal (10.8.4). Now that I've had my fingers burned I'll wait and see for awhile before upgrading again.
Now to clean up the Mac Pro...