I have been in the process of rebuilding my Plex Server and restoring the data. I popped in four 4TB WD Red NAS Drives and attached them to my 12G Controller. I figured it would be easy to create a datastore across the Raid 5 Drive and contine on my way. Unfortunately that was not the case, and I kept recieving errors similar to the one seen below.
While rather annoying, what I believe happens is that the Drives had a previous partition on them that ESXi just can not read or write to. So what we have to do is do some configuration in the ESXi Shell.
First we need to enable SSH on this host, which is very simple. At the Host Tab, click Actions -> Services – Enable Secure Shell (SSH). ESXi will enable the service and pop up a reminder warning for you.
Next we SSH into our ESXi Host.
We then need to determine the Disk ID of the Device we wish to fix. For us this is easy, as ESXi appends this to the name of the Device under Storage ->Devices. 
From there we go back to the Shell and cd to /dev/disks where we should see a bunch of disk IDs.
Then we run partedUtil mklabel /dev/disks/diskid msdos
Then we run through the steps to create the new Datastore and after a bit of a wait we should see the new Datastore created.
So there we have it, we have our Plex Datastore and I can create my new disk and start sharing my Media much to my fiancee’s enjoyment. She has really missed her Power Rangers. Also don’t forget to turn off SSH access for safety’s sake.
