Hey guys,

 

Recently Disk 4 was shown unmountable. I tried to get it to mount again, but since it is btrfs, my repair options are limited, especially when you can't mount it. 

 

I decided to replace it with a bigger drive, but since that drive was bigger than parity, I decided to do the parity swap procedure (https://wiki.lime-technology.com/The_parity_swap_procedure).

 

I followed the instructions 1 by 1. But after step 13 completed after 12 hours or so (copying parity to new disk), I wasn't sure if I should format Disk 4 (which is the old parity drive), since that Disk still has shown unmountable. I proceeded the instructions assuming that unraid would do the formatting for me and it began the data drive rebuild which lasted around 20 hours. Now, after everything is supposed to work again, Disk 4 is still shown unmountable. I am now scared that the data is lost since it basically rebuild parity by rebuilding the disk (or did it not?).

 

It does not seem like there are files missing, and I don't really have a way to determine if there are files corrupted. 2 out of 20 movies that I open with VLC don't work and seem corrupted, maybe it is a coincidence, though.

 

Also, wasn't unraid supposed to format the new Disk 4 for me? Maybe it is the controller's fault and all Disk 4's would be unmountable?

 

Should I just format Disk 4 and then start a parity check?

 

Attached are the diagnostics. I also still have the old drive, but again, since it is btrfs, probably unusable, unless it was the controller's fault.

 

Thanks in advance!

unraid-diagnostics-20170714-1227.zip

Rebuilding a disk won't fix file system corruption, to try and recover data from disk4 see this:

 

 

Thanks! Should I try that on the old drive or the new one, or does the new one not contain any data at all? Tried it on the new one and it said wrong fs type, bad option, bad superblock on /dev/sdf1, missing codepage or helper program, or other error

 

EDIT: Actually, the second method, btrfs restore, works on the new one. It copies some known files.

 

Unfortunately, I don't have enough space on a single disk anywhere. Is there some method to determine how much free space is needed? One possible way would be to either erase the old, unused drive or the new one to get enough space.

 

Is it possible to recover to the array share itself, eg. /mnt/user/nas ? How can I get Disk 4 out of the equation, eg. is it bad when I recover to the global share, even though Disk 4 is unmountable, and can I just format it when I'm done?

Edited July 14, 20178 yr by Beaving

If all went well with the swap both contain the same thing.

 

You could format the new disk4 then btrfs restore from the old disk to the new disk.

Thanks. I will make sure to donate a bit in case you PM me a bitcoin/PayPal address. Data is priceless.

 

I somehow don't trust the new drive and not the old drive either, therefore don't want to risk erasing one. Would it be safe to restore to the global share, then format Disk 4 after recovery? Or could those files be corrupted again when I delete Disk 4, even though it was unmountable?

2 minutes ago, Beaving said:

Would it be safe to restore to the global share, then format Disk 4 after recovery?

 

Yes, as long as you have enough space on the other disks it's OK.