e2image

E2IMAGE(8)                  System Manager's Manual                 E2IMAGE(8)



NAME
       e2image - Save critical ext2/ext3 filesystem metadata to a file

SYNOPSIS
       e2image [ -rsI ] device image-file

DESCRIPTION
       The e2image program will save critical ext2 or ext3 filesystem metadata
       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 assist an expert in recovering
       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, so that the output can be piped to another program, such as
       gzip(1).  (Note that this is currently only supported when creating a
       raw image file using the -r option, since the process of creating a
       normal image file currently requires random access to the file, which
       cannot be done using a pipe.  This restriction will hopefully be lifted
       in a future version of e2image.)

       It is a very good idea to create image files for all of filesystems on
       a system and save the partition layout (which can be generated using
       the fdisk -l command) at regular intervals --- at boot time, and/or
       every week or so.  The image file should be stored on some filesystem
       other than the filesystem whose data it contains, to ensure that this
       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 the 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 will 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.

RESTORING FILESYSTEM METADATA USING AN IMAGE FILE
       The -I option will cause e2image to install the metadata stored in the
       image file back to the device.    It can be used to restore the
       filesystem metadata back to the device in emergency situations.

       WARNING!!!!  The -I option should only be used as a desperation measure
       when other alternatives have failed.  If the filesystem has changed
       since the image file was created, data will be lost.  In general, you
       should make a full image backup of the filesystem first, in case you
       wish to try other recovery strategies afterwards.

RAW IMAGE FILES
       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 directory blocks, which the standard image file
       does not have, although this may change in the future.

       Raw image files are sometimes used when sending filesystems to the
       maintainer as part of bug reports to e2fsprogs.  When used in this
       capacity, the recommended command is as follows (replace hda1 with the
       appropriate device):

            e2image -r /dev/hda1 - | bzip2 > hda1.e2i.bz2

       This will only send the metadata information, without any data blocks.
       However, the filenames in the directory blocks can still reveal
       information about the contents of the filesystem that the bug reporter
       may wish to keep confidential.  To address this concern, the -s option
       can be specified.  This will cause e2image to scramble directory
       entries and zero out any unused portions of the directory blocks before
       writing the image file.  However, the -s option will prevent analysis
       of problems related to hash-tree indexed directories.

AUTHOR
       e2image was written by Theodore Ts'o (tytso@mit.edu).

AVAILABILITY
       e2image is part of the e2fsprogs package and is available from
       http://e2fsprogs.sourceforge.net.

SEE ALSO
       dumpe2fs(8), debugfs(8)




E2fsprogs version 1.39             May 2006                         E2IMAGE(8)