UNMOUNTABLE: NOT MOUNTED Disk, repair failed - can Parity save the data?

[fatefree]

Hello, I woke up this morning to a bunch of movies missing from my media library and I noticed one of my drives was unmountable. I attempted the repair steps and it sort of completed successfully, but the lost+found folder had tons and tons of files and some without any extentions, so I really didn't trust the drive contents anymore.

 

I stopped the array unassigned the disk, swapped in a new drive, and parity is in the process of building. But even though its writing, it still says the new disk is unmountable. I was hoping that after parity that would be fixed but I'm growing less confident as I read about this. Is this a scenario where Parity won't be able to help? Would parity rebuild with the unmountable disk, effectively erasing the backup of the dead drive? Or would parity stay intact and allow me to replace the unmountable drive and save the contents?

 

I'm very nervous about a scenario where a disk died and parity is no help, so I'd appreciate any info.

[JonathanM]

Parity rebuilds exactly what is emulated at the time the disk is removed, corrupt or not.

 

Parity does NOT have files, it only emulates the entire drive, filesystem as is.

 

Now that you have replaced the drive, you should try doing a filesystem repair on the rebuilt drive, perhaps it may have better results, but only if parity was out of sync when the drive was removed. If parity was synced up, the rebuilt drive will be an exact copy of the drive that you removed. That's the point of parity.

 

Filesystem corruption making the drive unmountable is not the same thing as a disk dying.

 

Attach the diagnostics zip file to your next post if you want more informed feedback.

[fatefree]

Thank you very much for the explanation - its a bummer but at least I understand the reasons. In my scenario after parity rebuilt, the drive was identical to the previous and the repair had the same result. I'm currently going through the lost+founds - my biggest fear of course is that the files in here could be incomplete. I haven't seen any evidence of that (most of these files were movies or tv shows), and although individual files/seasons may be missing, anytime a file is there it appears to be complete. I am hoping that the repair tool would only put files here that were intact so I can trust them without having to watch them all haha.

 

I am in the process of implementing better backups to prevent the sting of something like this in the future. I'm still not sure how this happened since there was no unclean shutdown and the drive was fairly new and precleared. It even seems like I can use the drive that failed again after another preclear - would that be a bad idea in your opinion?

 

I attached my logs in case it helps anyone else. Thanks again for explaining everything to me.

unraid-diagnostics-20220325-1501.zip check-2