[6.9.2] Unmountable disk being rebuilt

[nerbonne]

I just replaced a 4TB drive with a 6TB drive, but the new drive says "unmountable", even though the array is currently rebuilding....  Seems like the rebuild will finish and I'll still have an unmountable drive which means the data is lost?  Can someone please advise what I should do?

 

[JorgeB]

Please post the diagnostics: Tools -> Diagnostics

[nerbonne]

Hi, thanks for the reply.  Diagnostics attached.

tower-diagnostics-20210419-1934.zip

[JorgeB]

Once the rebuild is done check filesystem on that disk:

https://wiki.unraid.net/Check_Disk_Filesystems#Checking_and_fixing_drives_in_the_webGui

 

[nerbonne]

OK, i'm somewhat concerned that once the rebuild finishes, the data on that drive will be gone.  Can't I cancel the rebuild, put the original drive back in, and do new config?  The old drive is still good and has all the data on it.

[JorgeB]

27 minutes ago, nerbonne said:

OK, i'm somewhat concerned that once the rebuild finishes, the data on that drive will be gone.

It shouldn't, but next time you should attempt to fix the filesystem on the emulate disk before rebuilding, just in case it isn't.

 

Let it finish, you can still do a new config in the end if needed.

[nerbonne]

Ok, I waited until the rebuild was done, put the array in maintenance mode, ran xfs_repair, but it just scrolled FOREVER, so I got impatient and turned it off, put the original drive back in, new config, and now parity is rebuilding.  

 

That being said, can you explain "next time you should attempt to fix the filesystem on the emulated disk before rebuilding".  Any time I put in a disk, it automatically starts a rebuild.  How exactly do you do what you are suggesting?  Should a new/replacement disk just be formatted automatically?  Why did unRaid try to re-use the existing file system...

[itimpi]

58 minutes ago, nerbonne said:

That being said, can you explain "next time you should attempt to fix the filesystem on the emulated disk before rebuilding".  Any time I put in a disk, it automatically starts a rebuild.  How exactly do you do what you are suggesting?  Should a new/replacement disk just be formatted automatically?  Why did unRaid try to re-use the existing file system...

The rebuild puts on a replacement disk exactly what unRaid thinks is on the “emulated” disk.     You can therefore run the file system repair against the emulated disk BEFORE putting in a replacement disk.   If the repair of the emulated disk does not work then not much point in rebuilding as the rebuilt disk will have the same problems and you need to try an alternative method of getting your files back (e.g. original disk, backups).

 

1 hour ago, nerbonne said:

Ok, I waited until the rebuild was done, put the array in maintenance mode, ran xfs_repair, but it just scrolled FOREVER

What was showing while it was  scrolling?    This is not normal and in most cases the xfs_repair is a very fast process.

[nerbonne]

What was showing while scrolling: Just dots like this ................

 

Forever, screens and screens and screens of them.

 

The emulated disk didn't have any errors, as the original disk didn't have errors.  The problem was that the replacement disk was not imported properly...  How can I prevent that in the future.  Seems like I should have been asked something like "replacement disk does not have a mountable file system, do you really want to start a rebuild", in which case, I would have said no and used a different disk.

 

Anyways, I do appreciate all the support.  The original disk is back in, parity is rebuilding, no data lost (unless the disk fails during parity rebuild...  )  I formatted the replacement disk in Windows to wipe any Linux stuff, and I plan on trying to swap the disks again when the parity rebuild is complete.

[itimpi]

Just now, nerbonne said:

What was showing while scrolling: Just dots like this ................

That would only happen if no file system superblock can be found and the repair process starts looking through every sector on the disk to see if it can find a backup copy.   This sometimes works but also often means that the file system corruption is sufficient to stop the repair process working.   Any rebuilt drive would have exactly the same behaviour as it is simply a sector-for-sector copy of the emulated drive.   That is one reason why it is recommended you try to repair the emulated drive first as a successful repair only takes a minute or so.   If you cannot repair the emulated drive you will not be able to repair the rebuilt one either.