e2image - Save critical ext2 filesystem data to a file
e2image [ -r ] device image-file
The e2image program will save critical filesystem data on the ext2
filesystem located on device to a file specified by image-file. The
image file may be examined by dumpe2fs and debugfs, by using the -i
option to those programs. This can be used by an expert in assisting
the recovery of catastrophically corrupted filesystems. In the future,
e2fsck will be enhanced to be able to use the image file to help
recover a badly damaged filesystem.
If image-file is -, then the output of e2image will be sent to standard
output.
The -r option will create a raw image file instead of a normal image
file. A raw image file differs from a normal image file in two ways.
First, the filesystem metadata is placed in the proper position so that
e2fsck, dumpe2fs, debugfs, etc. can be run directly on the raw image
file. In order to minimize the amount of disk space consumed by a raw
image file, the file is created as a sparse file. (Beware of copying
or compressing/decompressing this file with utilities that don't understand
how to create sparse files; the file will become as large as the
filesystem itself!) Secondly, the raw image file also includes indirect
blocks and data blocks, which the current image file does not
have, although this may change in the future.
It is a very good idea to periodically (at boot time and every week or
so) to create image files for all of filesystems on a system, as well
as saving the partition layout (which can be generated using the using
fdisk -l command). Ideally the image file should be stored on some
filesystem other that the filesystem whose data it contains, to ensure
that its data is accessible in the case where the filesystem has been
badly damaged.
To save disk space, e2image creates the image file as a sparse file.
Hence, if the image file needs to be copied to another location, it
should either be compressed first or copied using the --sparse=always
option to GNU version of cp.
The size of an ext2 image file depends primarily on the size of the
filesystems and how many inodes are in use. For a typical 10 gigabyte
filesystem, with 200,000 inodes in use out of 1.2 million inodes, the
image file be approximately 35 megabytes; a 4 gigabyte filesystem with
15,000 inodes in use out of 550,000 inodes will result in a 3 megabyte
image file. Image files tend to be quite compressible; an image file
taking up 32 megabytes of space on disk will generally compress down to
3 or 4 megabytes.
e2image was written by Theodore Ts'o (tytso@mit.edu).
e2image is part of the e2fsprogs package and is available from anonymous
http://e2fsprogs.sourceforge.net.
dumpe2fs(8), debugfs(8)
E2fsprogs version 1.27 March 2002 E2IMAGE(8)
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