Provided by: e2fsprogs_1.45.3-4ubuntu2_amd64 bug

NAME

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

SYNOPSIS

       e2image [ -r|Q ] [ -f -b superblock ] [ -B blocksize ] [ -fr ] device image-file
       e2image -I device image-file
       e2image -ra [ -cfnp ] [ -o src_offset ] [ -O dest_offset ] src_fs [ dest_fs ]

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.

       When  saving  an  e2image  for  debugging purposes, using either the -r or -Q options, the
       filesystem must be unmounted or be mounted read/only, in order for the image file to be in
       a  consistent  state.   This  requirement  can  be overridden using the -f option, but the
       resulting image file is very likely not going to be useful.

       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.

       Option -b superblock can  be  used  to  get  image  from  partition  with  broken  primary
       superblock.  The partition is copied as-is including broken primary superblock.

       Option -B blocksize can be used to set superblock block size. Normally, e2fsck will search
       for the superblock at various different block sizes in an attempt to find the  appropriate
       blocksize. This search can be fooled in some cases.  This option forces e2fsck to only try
       locating the superblock at a particular blocksize. If the superblock is not found,  e2fsck
       will terminate with a fatal error.

       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.

       You can convert a qcow2 image into a raw image with:

            e2image -r hda1.qcow2 hda1.raw

       This can be useful to write a qcow2 image containing all data to a sparse image file where
       it  can  be  loop mounted, or to a disk partition.  Note that this may not work with qcow2
       images not generated by e2image.

       Options -b superblock and -B blocksize can be used same way as for raw images.

INCLUDING DATA

       Normally e2image only includes fs metadata, not regular file data.  The -a option  can  be
       specified  to  include all data.  This will give an image that is suitable to use to clone
       the entire FS or for backup purposes.  Note that this option only works with  the  raw  or
       QCOW2  formats.  The -p switch may be given to show progress.  If the file system is being
       cloned to a flash-based storage device  (where  reads  are  very  fast  and  where  it  is
       desirable  to  avoid unnecessary writes to reduce write wear on the device), the -c option
       which cause e2image to try reading a block from the destination to see if it is  identical
       to  the block which e2image is about to copy.  If the block is already the same, the write
       can be skipped.  The -n option will cause all of the writes to be no-ops,  and  print  the
       blocks that would have been written.

OFFSETS

       Normally  a  filesystem  starts at the beginning of a partition, and e2image is run on the
       partition.  When working with image  files,  you  don't  have  the  option  of  using  the
       partition  device, so you can specify the offset where the filesystem starts directly with
       the -o option.  Similarly the -O option specifies the offset that should be seeked  to  in
       the destination before writing the filesystem.

       For  example,  if  you have a dd image of a whole hard drive that contains an ext2 fs in a
       partition starting at 1 MiB, you can clone that fs with:

            e2image -aro 1048576 img /dev/sda1

       Or you can clone a fs into an image file, leaving room in the first MiB  for  a  partition
       table with:

            e2image -arO 1048576 /dev/sda1 img

       If you specify at least one offset, and only one file, an in-place move will be performed,
       allowing you to safely move the filesystem from one offset to another.

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)