Data Corruption with New Configuration Setup

[Nezuko Kamado]

I have the following configuration. When removing the failed disk, I used the https://docs.unraid.net/legacy/FAQ/shrink-array/ guide to remove the drive. 

The issue happened when I accidentally Swapped parity and data disk1 (both 14 TB) and started rebuilding. Fortunately, I realized that pretty quickly and was able to stop this.

The Parity says it's invalid, and disk1 is also not in great shape. To fix this

1. Is it possible to restore the parity drive?

2. revert the corruption on the disk1 data drive.

 

I have ordered another 14 TB drive and started using UFS Explorer to recover disk1 on a separate computer.

[dboonthego]

 

7 hours ago, Nezuko Kamado said:

I have the following configuration. When removing the failed disk, I used the https://docs.unraid.net/legacy/FAQ/shrink-array/ guide to remove the drive. 

The issue happened when I accidentally Swapped parity and data disk1 (both 14 TB) and started rebuilding. Fortunately, I realized that pretty quickly and was able to stop this.

I'm slightly confused.  Were you trying to make your array smaller by removing disk1 and 14TB of space?   Or did disk1 fail and you followed the shrink array procedure to rebuild it?  What steps did you follow exactly?  Right now, parity is invalid and disk1 is missing. 

 

[Nezuko Kamado]

okay. this might clarify what happened.

Configuration before Shrinking

Parity - 14TB

Disk1 - 14 TB

Disk2 - 10 TB

Disk3 - 8 TB

..... Disk7 - 2 TB (failed)

To compensate/To Remove the failed Disk I followed the guide https://docs.unraid.net/legacy/FAQ/shrink-array/
After removing failed drive I should I selected good configuration and should have started the array.
But at the time of selection, Unraid didn't populated any of the Disks. So I chose Parity and Disk1 incorrectly ( same size) and that caused all the issue

[Nezuko Kamado]

I followed https://docs.unraid.net/legacy/FAQ/shrink-array/#the-remove-drives-then-rebuild-parity-method this method of removing failed drive and rebuilding parity

[itimpi]

3 hours ago, Nezuko Kamado said:

I followed https://docs.unraid.net/legacy/FAQ/shrink-array/#the-remove-drives-then-rebuild-parity-method this method of removing failed drive and rebuilding parity

 

If all the data drives are as you want them (including nothing in the disk1 slot) then you could use Tools-<New config with the Preserve all option and then correct the parity disk assignment before starting the array to commit the change and start building new parity based on the new data disk set.

 

One question - what made you think that disk1 had failed?   A drive can be disabled for all sorts of reasons other than the drive actually failing with by far the most common being issues with the SATA or power cabling to the drive.

[dboonthego]

As I understand it, you performed a New Config and flipped parity and disk1 while also unassigning disk7?  Then started the array and noticed your mistake, and stopped it?  You would have seen a notice on parity disk showing "All existing data on this device will be OVERWRITTEN when array is Started" which you likely overlooked expecting you had set the parity correctly. 

 

What is the status of Disk7?  Is it truly failed, or you did you simply see an X after unassigning it?

 

The way I see it...

• Parity is fine. 
• Disk1 is toast
• Disks 2-6 are fine.
• Disk7 is questionable.  (This is disk you tried to shrink)

 

Your original parity is based on having disks 1-7.  *If* disk7 can be mounted and has no read errors, I'm thinking you can rebuild your disk1 like this..

1. Do another new config.  This time making sure you get it right.
2. Assign everything back to your original config...  Assign disks 1-7 making sure you put original parity in parity slot.
3.  ^^ You can assign your newly purchased 14TB as disk1 (keeping original disk1 in-tact for possible recovery)
4. Click the tick box that says parity is already valid.
5. Start the array.
6. Disk1 should be unmountable, DO NOT FORMAT IT.
7. Stop the array.
8. Unassign Disk1.
9. Start the array.
10. Disk 1 is Disabled.
11. Stop the array.
12. Assign Disk1.
13. Start array to rebuild disk1 from parity.

 

This of course requires that Disk 7 is in good shape and you didn't otherwise mess with your orig parity disk.  Please have someone else on this forum confirm these steps are good before attempting.