Provided by: e2fsprogs_1.40.8-2ubuntu2_i386 bug

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)