Provided by: e2fsprogs_1.42-1ubuntu2_i386 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)