An error was found in my array, but I don't have a clue on what went wrong

[LEKO]

Is there any easy way to have a bit more detail an context on the error(s) found in Unraid.

In the screenshot (attached to this post), I noticed I had a parity error a couple of days ago. But I don't know exactly how to diagnose/interpret it. My guess at the moment is this:
1. Parity check ran.
2. An error was found and probably fixed (How I can know/tell for sure?)
3. The notification is reporting that.
4. The next parity check will run (next week).
5. If no errors are found, the message will change for "no error found" (or something similar).

But, what if I would like to find our more about that error? What if parity errors comes (always) on the same drive? What it's "never" fixed and/or I start to run into bad sectors? Basically, I would like to know how I could interpret error messages and logs and make them actionable if necessary.

Any tips/ideas?

[itimpi]

The problem is that it is not possible to pin the cause of a parity error to a particular drive.

• is your regularily scheduled parity check set to be correcting or non-correcting?   It is recommended that you have it set to non-correcting so that a mis-behaving drive does not end up corrupting parity.    If it IS set to be non-correcting then the error will quite likely keep occurring until you run a correcting check.
• you mention the next check running ‘next week’.   This is probably unnecessarily frequent, and most users run the check only once a month or even less frequently.

[nnhoang]

1 hour ago, itimpi said:

• It is recommended that you have it set to non-correcting so that a mis-behaving drive does not end up corrupting parity.

 

That's good advice, is setting it to non-correcting simply just unchecking 'Write corrections to parity' on the Main page?

[itimpi]

22 minutes ago, nnhoang said:

 

That's good advice, is setting it to non-correcting simply just unchecking 'Write corrections to parity' on the Main page?

Yes for a manual check.

 

for a scheduled check it is on Settings -> Scheduler where you set the schedule.

 

[Jerky_san]

I use the Dynamix File Integrity plugin to try to help me with this. It check sums all your files. So when you find a "parity error" you run the check sums check against it to see if you can find any bad files. Keep in mind though there a things that can cause parity errors like unstable overclock of memory, unstable overclock of cpu, bad memory, and other things. For me that is why it is nice to have check sums as well. If I run parity check a second time and the error is still there then I can run check sum checks and see if any of the files are showing bad. If not then perhaps it's an errant error. If yes then I need to do more research(memtests and stability tests) till I find whats going on there.

[LEKO]

Thanks for the advice. If the error persist, I'll have good next steps and stuff to look into.
I'll double-check the checksum thing. I think I have it set up, but not 100% sure.

As for "frequency", I'm ok with doing it once a week. I use Unraid purely for backup, so I don't mind "exercising" the CPU/drive/memory once a week.