Re: Restoring BTRFS partition

[Sean Bartell <wingedtachikoma@gmail.com>]

On Tue, Apr 20, 2010 at 10:25:34PM +0000, Alli Quaknaa wrote:
> I think I have found the real superblock you are talking about, but
> I'm afraid I may have written something in the first 64MiB. Is there a
> chance btrfsck will recover it?
btrfsck is currently very limited; it only detects a limited number of
problems, and it can't fix anything. Btrfs focuses on handling problems
when they are discovered while using the FS; generally, it should handle
corruption relatively gracefully. However, if anything really crucial
was overwritten and the FS can't be mounted, there aren't any tools to
repair it.

> Also, I think there's gotta be a better way to manipulate those huge
> files then dd and hexedit for examination - I'd like to take the raw
> file, open it in some hex editor and be able to cut of some of it's
> beginning - I can't seem to be able to do it with hexedit. Is there a
> tool you'd recomment?
For viewing, you can use less, head, and tail with hexdump:
    tail -c +$((0x10000+1)) /dev/sda1|hexdump -C|less
will view the disk starting at the superblock. For editing, dd is
probably best, though you could use a hex editor like Okteta. I've also
heard of Radare, supposedly a very advanced command-line tool. Keep in
mind that any tool that deletes the first part of a huge file will be
forced to rewrite the entire file.