Hi Team, 

 

This month, Unraid performed a Scheduled Parity Check, and it detected errors:

 

"Scheduled Non-Correcting Parity-Check 2025-03-07, 11:23:48 (Friday) 16 TB 2 days, 22 hr, 51 min, 17 sec 62.7 MB/s OK 34552 5 days, 14 hr, 48 min, 37 sec 12"

 

I didn’t pay much attention to it because I still had access to my data, and everything was working fine. I assumed the issue had been fixed since the "Write corrections to parity" option was enabled, meaning it should have written over the bad sectors.

 

I noticed nothing unusual—everything worked as expected. Then, I decided to update to version 7.0.1, and after rebooting, Unraid no longer recognized Disk 8, marking it as "Invalid Disk."

At that moment, I realized that I had lost all the data on that disk—5TB gone. I panicked. Neither Unraid’s support, nor the forum, nor I could find a solution.

 

This whole situation made me question something critical:

👉 Is Unraid really stable, and can it guarantee data safety?

 

After checking the array and logs, the SMART data for Disk 8 (a brand-new drive) showed no issues. According to Unraid, there was data corruption, and that corruption was written to the parity disk, causing the data loss.

 

I then attempted a Rebuild Data, which took four days to complete. By that point, I had already come to terms with the fact that I would lose some data. And sure enough, after the rebuild was finished, the data was gone.

 

 

 

 

LOGS  -  https://drive.google.com/file/d/1AI2LIp7n1J0UPY-gENrh34IcJPVaOGMe/view?usp=sharing

 

After completing the data rebuild, I saw a message prompting me to format the disk. I went ahead and formatted it, and now it appears in the array.

I'm currently running a SMART test to check for any errors.

I've lost my data, and I feel extremely frustrated.

 

  

1 hour ago, Fiyors said:

At that moment, I realized that I had lost all the data on that disk—5TB gone. I panicked. Neither Unraid’s support, nor the forum, nor I could find a solution.

You hadn't, and it's your first post here... had you asked you'd have been pointed to the manual you could have also looked up on your own, particularly the section about "drive unexpectedly becoming unmountable":

https://docs.unraid.net/unraid-os/troubleshooting/data-recovery/#unmountable-disks

 

Quote

IMPORTANT: At this point, the Unraid GUI will be offering an option to format unmountable drives. This will erase all content on the drive and update parity to reflect this making recovering the data impossible/very difficult so do NOT do this unless you are happy to lose the contents of the drive.

 

1 hour ago, Fiyors said:

👉 Is Unraid really stable, and can it guarantee data safety?

It's stable, but nothing in the world can guarantee data safety, especially not on consumer setups. The only data safety you ever get is backup copies of anything important on completely independent hardware.

Edited March 15, 20251 yr by Kilrah

1 hour ago, Fiyors said:

After completing the data rebuild, I saw a message prompting me to format the disk.

Formatting the disk is never part of a data rebuild, there's a warning about that:

 

 

As mentioned, when you have an unmountable disk, the first thing to do is to try and repair the filesystem, a rebuild cannot help with that.

 

Since the disk was formatted, the only option to try and recover the data would be to use a file recovery app, like UFS explorer.