"Slow down" bootup until all devices are available
It's Server.app that is creating that mysterious folder that's gumming up your works.

Stop the Server.app from launching when the server boots, and then you can create a cronjob that launches it via a .sh script. 

Script should just be something like 

#!/bin/bash
/Applications/Server.app


and like the person said in the one link, the cronjob entry would be something along the lines of

@reboot sleep 60 &amp;&amp; my_script.sh


That should give your RAID enough time to mount properly before Server.app pops up and creates that folder.