I have added a new drive to my array. But its performance has stopped. I shutdown the system, added the drive, and powered it back on.  Assigned the new drive as disk3 and started the array.  After it got done clearing (I didn't use the preclear script), the webpage showed all three drives as unformatted, and had I hit the Format button at this point, I'd be toast.  Stopped the array, started it back up, and only disk3 (the new one) showed as unformatted.  Format button worked as expected to create a filesystem on that drive.

I have added a new drive to my array. But its performance has stopped. I shutdown the system, added the drive, and powered it back on.  Assigned the new drive as disk3 and started the array.  After it got done clearing (I didn't use the preclear script), the webpage showed all three drives as unformatted, and had I hit the Format button at this point, I'd be toast.  Stopped the array, started it back up, and only disk3 (the new one) showed as unformatted.  Format button worked as expected to create a filesystem on that drive.

You must be on 4.5.3.  (or that is my best guess at the version of unRAID you are running)

 

That "all disks unformatted" bug is probably the worst bug to have hit unRAID.  Please upgrade to 4.7.  (The bug is not harmful "unless" you press the "Format" button and format all your disks. Several unRAID users did format all their disks though, and it was painful for them to recover.)  The issue was a "race" condition in mounting the disks.

 

As you said, stopping the array, and then re-starting it corrects the mounting of the disks and you can proceed to format only the new disk.

 

Joe L.