btrfs-progs/man/btrfs-image.8.in
Rakesh Pandit afb7de0da2 Btrfs-progs: remove unused variable and update btrfs-image man page
Remove unused variable in btrfs-image.c (update_super) and update man
page documentation about -r option. Running btrfsck on a restored
image produces missing chunk information. This is because by default,
btrfs-image fixes up chunk tree to use 1 stripe pointing to the
primary device. This in turns results in btrfsck making some noise.

$  ./mkfs.btrfs /dev/sdb2 -f
$  ./btrfs-image /dev/sdb2 btrfs_image_output
$  ./btrfs-image -r btrfs_image_output disk-image
$  ./btrfsck disk-image

Device extent[1, 29360128, 8388608] didn't find the relative chunk.
Device extent[1, 1111490560, 1073741824] didn't find the relative chunk.

Ideally btfsck should be updated to reflect this default behavior and
not through these messages, but it isn't harmful and can be done
later.

Signed-off-by: Rakesh Pandit <rakesh@tuxera.com>
Signed-off-by: David Sterba <dsterba@suse.cz>
Signed-off-by: Chris Mason <clm@fb.com>
2014-03-21 06:23:33 -07:00

56 lines
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.TH BTRFS-IMAGE 8
.SH NAME
btrfs-image \- create/restore an image of the filesystem
.SH SYNOPSIS
.B btrfs-image
[options] \fIsource\fP \fItarget\fP
.SH DESCRIPTION
.B btrfs-image
is used to create an image of a btrfs filesystem. All data will be zeroed,
but metadata and the like is preserved.
.I source
is the special file corresponding to the device containing a btrfs filesystem.
(e.g \fI/dev/sdXX\fP).
.I target
is the image file that btrfs-image creates. When used with \fB-r\fP option,
\fBbtrfs-image\fP restores the image file from source into target.
.SH OPTIONS
.TP
\fB\-r\fP
Restore metadump image. By default, this fixes super's chunk tree, by
using 1 stripe pointing to primary device, so that file system can be
restored by running tree log reply if possible. To restore without
changing number of stripes in chunk tree check \fB-o\fP option.
.TP
\fB\-c\fR \fIvalue\fP
compression level (0 ~ 9).
.TP
\fB\-t\fR \fIvalue\fP
number of threads (1 ~ 32) to be used to process the image dump or restore.
.TP
\fB\-o\fP
use the old restore method, this does not fixup the chunk tree so the restored
file system will not be able to be mounted.
.TP
\fB\-s\fP
Sanitize the file names when generating the image. One \fB-s\fP means just
generate random garbage, which means that the directory indexes won't match up
since the hashes won't match with the garbage filenames. Using \fB-ss\fP will
calculate a collision for the filename so that the hashes match, and if it
can't calculate a collision then it will just generate garbage. The collision
calculator is very time and CPU intensive so only use it if you are having
problems with your file system tree and need to have it mostly working.
.TP
\fB\-w\fP
Walk all the trees manually and copy any blocks that are referenced. Use this
option if your extent tree is corrupted to make sure that all of the metadata is
captured.
.SH AVAILABILITY
.B btrfs-image
is part of btrfs-progs. Btrfs is currently under heavy development,
and not suitable for any uses other than benchmarking and review.
Please refer to the btrfs wiki
http://btrfs.wiki.kernel.org for further details.
.SH SEE ALSO
.BR btrfsck (8), mkfs.btrfs (8)