Am I screwed? Dead drive during server upgrade after new config

[mysterio0]

Hi good people of the Unraid community. I recently reached the limit of my current setup and decided to upgrade to a bigger one. I have some Unraid experience, so I went in with what appears to be overconfidence in hindsight.

I moved all my drives to the new server and booted up Unraid and saw that the drive assignments had changed. I clicked new config and rebooted the server and at this point I noticed that one of my drives is not showing up. I then spent all day diagnosing and came to the conclusion that the drive is dead as it won't show up in the bios or my other PC.

Now I haven't booted the new server up again because I am not sure how to proceed and want to minimize the chances of me making mistakes that would result in data loss.

What are my options for recovering the data? I have a spare 10TB drive that I can use to replace the dead 8TB one. How do I go about setting up the array again and not lose data in the process? Any and all help is immensely appreciated.

[JorgeB]

We need more details, mostly what Unraid release are you using and if there's single or dual parity, as well as current parity size.

[mysterio0]

I am running Unraid 6.7.0 with a single 10TB parity drive.

[JorgeB]

Assuming parity is valid you can use the invalid slot command to rebuild the missing disk:

 

-Since you already did a new config assign all disks, including the new 10TB disk to replace the missing one, make sure old parity is correctly assigned to the parity slot, data disk order with single parity is not important, you can assign them as you like.
-Important - After checking the assignments leave the browser on that page, the "Main" page.

-Open an SSH session/use the console and type (don't copy/paste directly from the forum, as sometimes it can insert extra characters), replacing # with the missing disk number:

mdcmd set invalidslot # 29

e.g., if it's disk11 it would be:

mdcmd set invalidslot 11 29

 

-Back on the GUI and without refreshing the page, just start the array, do not check the "parity is already valid" box (GUI will still show that data on parity disk(s) will be overwritten, this is normal as it doesn't account for the invalid slot command, but they won't be as long as the procedure was correctly done), disk will start rebuilding and it should mount immediately but if it's unmountable don't format, wait for the rebuild to finish and then run a filesystem check