Provided by: e2fsprogs_1.42-1ubuntu2_amd64 bug

NAME

       e2image - Save critical ext2/ext3/ext4 filesystem metadata to a file

SYNOPSIS

       e2image [ -rsI ] device image-file

DESCRIPTION

       The  e2image program will save critical ext2, ext3, or ext4 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, or QCOW2 image 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, or in  QCOW2  format.
       Hence,  if  the sparse 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.
       This does not apply to the QCOW2 image, which is not sparse.

       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.

       Note that this will work even if you substitute "/dev/hda1" for another raw disk image, or
       QCOW2 image previously created by e2image.

QCOW2 IMAGE FILES

       The -Q option will create a QCOW2 image file instead of a normal, or raw  image  file.   A
       QCOW2  image contains all the information the raw image does, however unlike the raw image
       it is not sparse. The QCOW2 image minimize the amount of disk space  by  storing  data  in
       special  format  with  pack  data  closely  together,  hence  avoiding  holes  while still
       minimizing size.

       In order to send filesystem to the maintainer as a part of bug report  to  e2fsprogs,  use
       following commands (replace hda1 with the appropriate device):

            e2image -Q /dev/hda1 hda1.qcow2
            bzip2 -z hda1.qcow2

       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.

       Note  that  QCOW2  image created by e2image is regular QCOW2 image and can be processed by
       tools aware of QCOW2 format such as for example qemu-img.

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)