I'm going to preface this by saying "I have no concern for data loss - I am backed up three ways." So please have no concern for my data. I came here to be educated on this topic.

Storytime:

I had a bad 8087 x 4 sata cable that caused a bunch of UDMA CRC errors with a disk. I diagnosed it by swapping the cable to another disk and saw it build some crc errors during a parity check. I pulled the CRC failed disk out of caution and started rebuilding the removed disk with a tested spare. 

My curiosity asked - "Hey I wonder if I can mount this pulled unraid disk in another computer if I had to recover data?" Sure enough, I plugged it into a Fedora VM on my laptop using a usb enclosure and it was seen immediately and automatically mounted. I tested my skills unmounting it, running xfs_repair to check it and so forth. I plugged it into an OMV 5 server and was able to mount it and read the directory structure just fine as well.

Then I put it back in the unraid server and attempted to mount using unassigned devices - NO LOVE. Dropped into terminal and tried manually - unsuccessful - "error was wrong FS type". I tried again specifying -t xfs - still NO LOVE same error.

I put it back in the Fedora VM and it works perfectly fine I can mount it all day long. I ran some par2 checks on the stored data and it was fine.

I'm going to save the disk from further testing until its replacement is rebuilt in the server.

 

Can anyone tell me why I can't get it to mount in unraid? I used "mount /dev/sdl1 /mnt/old3" and "mount -t xfs /dev/sdl1 /mnt/old3" and had no success - both times gave me the wrong filesystem error message.

Edited January 25, 20224 yr by wildfire305

I found a clue:

Jan 23 02:05:52 CVG02 kernel: XFS (sdl1): Filesystem has duplicate UUID d0ba1183-2aa6-432f-9ae6-1c029498de77 - can't mount

I assume I need to generate a new UUID somehow since it was an array disk? Can anyone show me how to do that?

 

Something like this: https://www.tecmint.com/change-uuid-of-partition-in-linux/ ?

Edited January 24, 20224 yr by wildfire305

You can generate a new UUID with:

xfs_admin -U generate /dev/sdX1

 

P.S. next time you might want to post the diags, you'd get an answer sooner.

Worked like a charm. Thanks! I'm assuming that UUID was assigned to the array and I removed the disk from the array, the system was playing safe not letting the disk back in. Running a diff on it and the new disk 3 now for "peace of mind" comparison.

You can't have the same filesystem mounted twice, doesn't matter if one of them is in the array or not, e.g., if you cloned the disk with dd you couldn't them mount the original and the clone at the same time using UD.