I was building a new array, using drives formatted with larger cluster sizes to get over the 15.8TB drive limit.

Since you can't 'remove' a drive in the GUI and have everything rebalance, I physically removed the drive while powered down.  Upon rebooting, Storage Spaces said there was a missing drive and I clicked "Remove" so that the repair work would start (plenty of room since I'd just moved 7TB of data to the new array).

Then disaster hit.  One of my 1TB drives failed hours into the Repair process.

It appears the drive has failed - powers up, spins up but no computer can see it and it doesn't show up in the Disk Management tool.  I may have lost irreplaceable pictures and home movies.  I'd be using mirroring for just this reason.

HOWEVER - the 4TB drive I removed?  Haven't written a thing to it or used it in any way.  When I spin it back up, I get that Disk 14 is Healthy with "Storage Spaces Protected Partition".  Is there ANY way I can "re-attach" this disk to the array to make up for whatever was on the 50% of the 1TB drive that was mirrored on the 4TB drive?  Only files who were on those two disks and no others would be affected and those are the ones I'm worried about.

Thanks in advance.

Depending on what type of Storage Space you created, it would appear that you could replace the 1TB drive with a new one, and merely return the 4TB drive as before.

Once again, you'd get the notice that a "repair" is required... and it will start the rebuild.

It's telling me I have to replace the 1TB drive before it will allow me to 'remove' it - hopefully that will at least make the array visible.  I've plugged the 4TB drive back in and the DIsk Management Console sees it as the "Storage Spaces Protected Partition" - but Storage Spaces itself doesn't like it.  Now Storage Space sees it and says "Unrecognized configuration; reset drive".  Having read about what "reset drive" does, I do NOT want to do that as it will wipe out the data on that drive.