Thread: Help needed to do a backup
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DrYak is offline DrYak
2017-10-24 , 22:41
Posts: 248 | Thanked: 1,142 times | Joined on Dec 2014 @ Earth
#48
Originally Posted by Amboss View Post
Naah, almost everytime I tried something, it disconnected telnet. An everytime I tried again, I made it worse.
Actually, trying to fsck a BTRFS partition is a VERY BAD idea.
(Same applies for other CoW filesystems like ZFS and log-structured filesystems like UDF and F2FS).

The best is to always simply try to get an early version (before the "copy" part of Copy-on-Write).

For BTRFS, things that might help :
- mounting with "recovery" (will scan back the older copies until it finds the latest usable) (for kernel 4.6 and newer, its now called "usebackuproot")
- mounting with "nologreplay" (completely ignore the journal log)
- using "btrfs restore -s -x -m -S -i " on an image transfered to a laptop.

Originally Posted by Amboss View Post
When I write the new image to mmcblk0p28 everything seems fine, btrfs check gives no errors.
By write, you mean you DD an image file over the raw device.
Not that you mount the (perhaps corrupted) partition and untar your files inside ?

By check you mean mount and "btrfs scrub start" ?

Originally Posted by Amboss View Post
When doing another btrfs check, file system is now broken again with lots of csum erros and more.
To me, that looks like a broken btrfs partition.
If you have some place where I can send you the file (FTP server ? Something else ?) I can send you my recovery partition.

I just can't post it publicly, because it contain non-public code (mostly driver and blobs from Qualcomm which make it illegal to post online).
 

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