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MrPotter

Disk Failure, Replaced, Missing Data?

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Hey everyone,

 

I recently had my first disk fail ever in UNRAID (shocker, as a long time user!). I removed the drive which was a 5TB Toshiba X300 drive, and replaced Disk 5 with another 5TB Toshiba X300 (different model number). I put assigned the new disk to the failed drive slot, however once parity rebuilt (~13 hrs or so), I am missing all of the data that was on the drive. 

 

Now I can try to hook up the old drive externally and copy the data back, but I was under the impression that when parity rebuilt, all of the data would have been restored to the new disk. 

 

Did I miss a step somewhere? 

 

Thanks for any/all help!

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As long as you don't format the slot, all data should be rebuilt. If at any point in the process you selected the checkbox and formatted, you erased the emulated and rebuilt data.

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BTW, how do you know the disk actually failed, and it wasn't a communication issue?

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25 minutes ago, jonathanm said:

As long as you don't format the slot, all data should be rebuilt. If at any point in the process you selected the checkbox and formatted, you erased the emulated and rebuilt data.

 

The only format I did was on the new disk assigned into that slot after the old disk was removed. Did that totally screw me?

 

24 minutes ago, jonathanm said:

BTW, how do you know the disk actually failed, and it wasn't a communication issue?

 

The disk was throwing errors like crazy, I hadn't been in UNRAID for a few days, and had about 94 errors pertaining to that disk.

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23 minutes ago, MrPotter said:

The only format I did was on the new disk assigned into that slot after the old disk was removed. Did that totally screw me?

Yes. Format is never a part of rebuild. The whole disk is rebuilt, with the existing format applied. If you apply a new format, it erases the old one.

 

24 minutes ago, MrPotter said:

The disk was throwing errors like crazy, I hadn't been in UNRAID for a few days, and had about 94 errors pertaining to that disk.

Doesn't mean the disk itself was bad, it could have been the cable or port. Not saying it wasn't the disk, just that a disk that is actually fine but can't talk to the host will show errors.

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1 minute ago, jonathanm said:

Yes. Format is never a part of rebuild. The whole disk is rebuilt, with the existing format applied. If you apply a new format, it erases the old one.

 

Doesn't mean the disk itself was bad, it could have been the cable or port. Not saying it wasn't the disk, just that a disk that is actually fine but can't talk to the host will show errors.

So even though I took the old drive out, and clicked format on the new disk in the slot, that's what destroyed all the data? Shit, I wish I knew that or read more carefully. Lesson learned. Luckily I may still be able to access the XFS system on the old disk and copy data manually back to the new disk if it's not totally borked. Thanks for the clarification!

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Here's hoping the drive errors were actually a bad or loosened SATA cable and all your data is intact on the old drive.

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I'm not 10000% percent sure the drive had failed (I might have panicked). I'll review it externally when I get home from work today. Out of curiosity was there a section in the FAQ that says "DON'T FORMAT THE *NEW* DRIVE" before assigning to the old slot that I missed? If not, I think it might be beneficial to have it there so no one else makes the same stupid mistake I will never make again.

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It's probably in the FAQ, but more importantly it requires you to see the warning before it will allow you to format the disk.

Format.png

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I think I definitely misunderstood that part then and thinking it was referencing the old drive. This is very good to know for the future. Thank's for the photo as well - I 100% remember seeing that.

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4 minutes ago, MrPotter said:

I 100% remember seeing that.

Ok, now that it's clear what happened, how can we keep it from happening to other users? It's happened before, and it seems to be an ongoing thing.

 

What wording or changes with that warning could have prevented you from making that mistake?

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I thought I always had to format the new drive. It was 10/10 an operator error on my part, and the warning was referencing not formatting an old drive. How any changes (such as a format) could impact a drive that was removed from the system didn't really "click" in my head.

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