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Array will not start.. States disk I/O errors even with disk is physically not connected

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I had an unclean shutdown event that resulted in one of the disks in my array showing as offline following a reboot. It was the one disk in my array that was a ZFS disk that I use for saving cache drive snapshots to the array. 

This has happened before and doing the trick of starting the array with no drive in the pool slot and then stopping the array and re-adding the drive allows for a rebuild of the array. 

This time the array hangs starting "disk 7 experienced an uncorrectable I/O error." This causes the array to hang at "mounting disks" and not progress further with the rebuild. All the other disks are mounted and I can access the files. This happens even with the disk physically removed from the server. I cannot even start the array to get data off the emulated disk. I do not understand what is happening. 

I cannot get the array to rebuild my disk 7 now. Is this a ZFS issue? I have attached my diagnostic file.. If anyone can help. Otherwise, I am going to have to nuke this config and remake the array and probably lose the data on that one disk. 

Thanks anyone for any help. This is the first time I have encountered something that I cannot figure out on my own regarding UnRaid... 

 

image.thumb.png.3e571947b9e78a976bb459ed27089f39.png

 

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woodtower-diagnostics-20250214-1630.zip

Solved by JorgeB

  • Community Expert

When a zfs pool is suspended, Linux will hang, and you will need to force a reboot, do that, don't start the array and post the output from:

 

zpool import

 

  • Author
10 hours ago, JorgeB said:

When a zfs pool is suspended, Linux will hang, and you will need to force a reboot, do that, don't start the array and post the output from:

 

zpool import

 

image.png.813a65eeaf3c0ed338b7026900d60421.png

 

Here is what is shows. I had renamed the share on the drive at one point when I was trying to mount it outside the array. 

Thank you for responding to my question! 

  • Community Expert

Looks like the actual disk filesystem was also already damaged, see if you can import it in read-only mode:

 

zpool import -f -o readonly=on disk7_broken

 

  • Author

With the disk7_broken pool mounted as read only I am able to start the array. However now it shows disk 7 as being the wrong or no file system and it wants me format the drive. I cannot access any data on the drive. Is the data on the drive gone? How did this happen with a parity drive? 

  • Author

So with the drive mounted in read-only I figured out I can actually get to the files just not through the UnRaid GUI. I have moved all the files off the drive now. I will be replacing this drive. Hopefully it works this time. 

  • Community Expert
  • Solution
6 hours ago, [email protected] said:

I have moved all the files off the drive now. I will be replacing this drive. Hopefully it works this time. 

Yes, that is what I was going to suggest, the new disk will need to be formatted, then restore the data.

  • Author

That did end up working. I was not able to restore some of the data due to permissions issues but this was data that was just backups from other locations. Thanks for the help hopefully that won't happen again. 

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