Horrible noob mistake (data loss)


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I made a bad late night mistake, I had full ntfs drives in my unraid (HP microserver) and I did not understand that parity sync is not merely a scan but basically a rebuild. It didn't say 'warning your data might be erased', but I had second thoughts and cancelled it after like a minute.

 

:-\

 

 

One of the drives was not yet started at all (hoping that one could be recovered in full), but I'd like to recover as much of my data as possible. I guess I misunderstood and thought that drives of other file systems could be read by unraid.

 

What are my options?

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Your description does not completely agree with the way unRAID operates, so it's not clear what you have.

 

A parity sync will only rebuild the parity drive. Did you assign your NTFS drive as the parity drive?

 

Or did you add it to the array and unRAID began clearing it.

 

Not sure if it matters in terms of getting your data back. Maybe someone else has some experience with recovering NTFS data.

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Did you have the ntfs formatted drives assigned to slots in Unraid?  The first thing it has to do is format them, which makes unraid unavailable (that's why most of us use Joe L's preclear script to prep and stress test the drives prior to adding them).  So if you didn't have them assigned to slots, you should be fine.

 

If you did, then I'd suggest taking them out and mounting them in a Windows machine and see if you can access the data, or run repair tools on them to try and recover.

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If you put the drive in Windows and it shows up as unformatted or corrupt, you'll have to run some recovery programs like Active@ Partition Recovery. You could also try their file recovery to scan the whole drive to try and piece your files back together. If it finds partition pieces it can virtually mount them and you may have access to your data. You may be in luck since you stopped it after a minute. I've had success with that software on numerous occasions with hard drives, usb drives, and memory sticks. I've even recovered data from a drive that was quick formatted.

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  • 3 weeks later...

Hi, thanks for the replies.

 

I did set one of the drives to a parity drive. Doh!

 

But the drive that I wanted to recover was a different drive and was recoverable in full.

 

Still trying to wrap my head around this unraid stuff, like how large is a parity drive supposed to be in proportion to the rest of the array?

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Still trying to wrap my head around this unraid stuff, like how large is a parity drive supposed to be in proportion to the rest of the array?

The size of the parity drive is not mandated by the size of the array, but by the size of the largest drive in the array.  The parity drive must be the same size (or larger) as the largest data drive.

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Still trying to wrap my head around this unraid stuff, like how large is a parity drive supposed to be in proportion to the rest of the array?

The size of the parity drive is not mandated by the size of the array, but by the size of the largest drive in the array.  The parity drive must be the same size (or larger) as the largest data drive.

Yep. In semi-techie terms, I think of unRAID as just a bunch of disks (JBOD) with an added error correction disk (Parity).

 

Visually,  I picture unRAID as a series of 'books' of different heights on a shelf..tall books, short books, etc. At the end of the stack of books is one additional book (parity) that has the 'sum' of all the lines in all the other books reading across the shelf. That sum is computed by adding ACROSS the books. So the first line of each book is added together to get the first line of the Parity book.

In order for the Parity book to be large enough to be able to 'store' the last line of the tallest book, it needs to be at least the same height as the tallest book.

 

If I lose one of the data books (due to spontaneous combustion?) I can recreate it by using the parity book. For each line in Parity, I subtract the lines in the surviving books...the remainder is the line from the missing book.  Second line follows, etc.

 

Poor metaphor, but it works for me. :)

 

 

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