Thread: Help needed to do a backup
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2017-10-26 , 10:14
Posts: 237 | Thanked: 502 times | Joined on May 2010 @ Mittelfranken, Germany
#49
Originally Posted by DrYak View Post
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).
yes, seems I found that out the hard way. On the other hand, I didn't use any options other than what Jolla gave me at hand, which is: recovery menu with options 5, 1 and 4 (used them in that order after each failing) . Reaching No.4 the other two already broke everything.
Originally Posted by DrYak View Post
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.
Thx, will try these. Up until now I did a btrfs restore -ivso (which is btrfs 3.16) from device to sd card.
Originally Posted by DrYak View Post
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" ?
By write I mean DD
By check I mean unmounted btrfs check (without --repair)
Originally Posted by DrYak View Post
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).
One thing I found out lately: dmesg gives me a unsupported option (100). I guess the btrfs created on my laptop is not compatible with the old 3.16, so it won't mount. In the end this might cause the errors being created on first reboot, when J1 tries to repair automatically?
At the moment I try to create btrfs on device and the restore from dd image file.

I do not have a publicly writable storage for file transfer. Will see, if I can get a ftp server running temporarily.

Appreciate your help!