scrathe

I did a poor job of explaining what steps I took previously. I did xfs_repair -n, no -n (repaired), and another -n which reported no errors. Despite no errors, it still reported "Unmountable: not mounted".
 
Thank you trurl 🙏 for taking the time on this thread.
 
I was able to save my data. Posting the *cough solution below?... may some other poor soul who's thinking they lost data find help here.
 
TLDR; Run xfs_repair (without -n) before you run Data-Rebuild. Data-Rebuild didn't work the first time. Removed/readded the disk to the array and re-ran Data-Rebuild. Disk and array are back to normal.
 
Scenario:
Older/established server experienced a mini-SAS to 4-drive cable failure. (SFF-8643 to SFF-8482) Two drives were knocked offline. Parity2 and Disk1. unRAID array status reported: Disk1 was emulated. However the data, and total array space was missing. Disk1 was "Unmountable: not mounted". Powered down. Replaced cable. Removed Parity2. Left healthy Parity1 in place. Powered up. Started array, started Data-Rebuild. unRAID array status reported: Disk1 was emulated. Data and space still missing. Disk1 was "Unmountable: not mounted". Data-Rebuild completed: Disk1 is marked "green, in operation". Data and space still missing. Disk1 was "Unmountable: not mounted". Stopped array. Solution? It worked... not entirely sure if all steps are needed.
Started array (maintenance). Disk1: xfs_repair -n (100s and 100s of errors) Disk1: xfs_repair (repair without -n) Disk1: xfs_repair -n (no errors) Stopped array. Started array (normal). unRAID array status reported: Disk1 is marked "green, in operation". Data and space still missing. Disk1 was "Unmountable: not mounted". Stopped array. Removed Disk1 from array. Started array (maintenance). Stopped array. Added Disk1 to array. Started array (normal). unRAID array status reported: Disk1 was emulated. Data APPEARED, and total array space was BACK. Disk1 was "Unmountable: not mounted". Started Data-Rebuild. Data-Rebuild completed: Disk1 back to NORMAL.