I replaced a data drive with a larger one, started the array and the rebuild process.  91% done and the (only) parity drive fails.  I can't start the array, and I can't put the old data drive back because unraid is expecting the larger one.

 

Is there a way to force unraid to use the older, smaller drive in place of the larger one that didn't finish being rebuilt?  Even better, is it possible to keep the existing data so I don't lose it?

 

What I'd like to do is revert the data drive back to the original one, without losing data.  And then use the new larger drive to replace my failed parity drive.

Put old drive back in and replace parity with new drive. Go to Tools - New Config. Retain ALL then make the necessary assignments changes. Don't check the parity is valid box and start the array to build parity.

That worked!  Thank you so much!