itimpi

Unraid uses standard Linux file systems, so the drives can always be read there outside Unraid if needed.   Each array drive is a self-contained file system and can be read by itself.

Unraid does not put (or require) anything into the appdata directory.   The fact you have it means it must have been created by something you installed.  

I would check file system on the drives associated with the shares as file system level corruption has been known to cause this sort of issue.

You can make the changes without stopping anything
 
Having said that if you are on the 6.12.x releases you can get the same performance benefit without making any changes to paths by doing the following:
Make sure that Permit Exclusive shares is enabled under Settings->Global Share Settings Set the pool to be primary storage with no secondary storage (equivalent to Cache Only in earlier releases) make sure that all files for the share are on the pool.    You will now be able to activate Exclusive mode in the share settings. with these changes you get the same performance whether you go direct or via the User Share path.

If that was the case then I would consider returning them - they are obviously not new.

Not a comment on your diagnostics, but you want to make sure your UPS is NOT set to run Unraid as long as it can, but is set to initiate a shutdown with plenty of power left.    You also do not want the Unraid server set to automatically power on as soon as power is supplied as it means it can come on before the UPS has a chance to recharge.

You can disable a plugin without actually removing it by renaming the .plg file to have a different extension and rebooting.   It then becomes a matter of trial-and-error.
 
You are likely to get better informed feedback if you attach your system’s diagnostics zip file to your next post in this thread so we can see what plugins you are running.

The only part of the USB drive that really matters is the ‘config’ folder and all its contents as that is where all user settings are stored.   However most people seem to like having the Unraid system files as well.

If the drives were on the LSI controller on the old system and will also be on the new system then order is irrelevant.    Unraid recognises drives by serial number - not by where they are connected.   There is only ever a problem if as part of the upgrade the controller type is changed and this results in the disk getting presented differently to the host.  Most likely to happen when RAID controllers are involved rather than simple HBA ones.

You could use the Dynamic File Manager plogin on the Unraid side to do this I believe as it can mount remote shares.

This means you want files moved TO the flash drive - is this what you want?
 
you might want to check that you have a sensible value for the Minimum Free Space setting for the cache drive and the User Shares

I suggest you follow the procedure documented here in the online documentation to rewrite the system files.
 

Unraid has to format its disks to get them correctly partitioned and formatted (which wipes any existing contents).
 
you need at least 1 drive with no content to get started.    This can then be added and formatted as the first disk in the Unraid array.    If you then install the Unassigned Devices plugin this will allow you to mount NTFS drives so that you can copy the content off onto the array drive.   The Dynamix File Manager plugin can help with this.  Once the drive has all its content removed the drive can then be added to the Unraid array to give additional space.   Repeat as many times as needed.
 

You can check that the file /etc/cron.d/root contains entries for those.   If not trying making a change on the User Scripts settings page and apply it to try and regenerate the entries.

You might want to delete (or rename) the config/vfio.cfg file on the flash drive.    There is a good chance that with a new motherboard the device ID's for passed through devices are different.

It is not certain from your description if it is the new drive you have just added or not,  At this point I would suggest running a correcting parity check (which should report the same 2 errors as it corrects them), and then run another non-correcting check which should now report 0 errors.  
 
if you still have errors reported then please post your diagnostics. 

Not using standard features as Unraid only supports top level shares
 
Should be able to do it if you are prepared to five under the covers to do manual configuration but this would be error prone.

Normally closing the window also kills the process.
 
You could look at using ‘screen’ to get around this limitation.   I know screen can be installed via the NerdTools plugin.   You can use Google to get instructions on running ‘screen’.

The file on the flash drive config/shares/Music.cfg is corrupt.  All .cfg files should be human readable and that file is not.  You should delete it and after doing that go into the Music User share settings and check they are what you want as they will have reverted to default settings.
 
I would suggest you also do the following:
Put the flash drive into a PC/Mac and let it check it for consistency. Make a backup of the config folder from the flash drive in case the corruption indicates a potential problem with the flash drive.

The only thing I might do differently is use btrfs for the pools, but this mainly because I am familiar with it and not yet as much with ZFS as it is new to Unraid.

Yes.

What you want is not possible.   However an alternative approach (as long as you are on the 6.12.x release) might be to use the 2 10TB drives in a ZFS pool instead.

These are not normally an issue unless they are increasing at a steady rate.    They indication connection issues between the drive and the host machine and are typically caused by power or SATA cabling issues.   If one is encountered then the host will retry the transfer so the typical impact is just to slow things down unless the retries all fail and as a result a transfer actually fails.  It is worth noting that the CRC count never resets to 0 so once you have some if you can stop them increasing you have fixed the issue.

This is a typical speed for the main array when it has parity protecting and more than one data drive.    Your previous configuration was a special case as with one parity drive and one data drive they act as mirrors.   You may get better speeds if you enable Turbo Write mode, albeit at the cost of having all drives spinning when writing to the array.
 

It does - you can only rebuild to the same file system as the parity rebuild process is unaware of file systems as it work at the raw sector level.
 
If you tried to format it you would have got a popup warning you that this would erase all data, update parity accordingly and that a format is never part of a rebuild. It looks like you continued with the format anyway?
 
If you still have the old 6TB drive untouched you should be able to mount it using Unassigned Devices to get the data back.