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

NAME
       e2image - Save critical ext2/ext3/ext4 filesystem metadata to a file
SYNOPSIS
       e2image [ -r|Q ] [ -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 cat-
       astrophically corrupted filesystems.  In the  future,  e2fsck  will  be
       enhanced  to be able to use the image file to help recover a badly dam-
       aged 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 require-
       ment can be overriden 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 dam-
       aged.
       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  com-
       press 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  filesys-
       tem 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 under-
       stand how to create sparse files; the file will become as large as  the
       filesystem  itself!)   Secondly, the raw image file also includes indi-
       rect 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 infor-
       mation 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  prob-
       lems 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 for-
       mat 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  infor-
       mation  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 prob-
       lems 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.
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 pur-
       poses.  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 AT 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 1.42.9         December 2013                      E2IMAGE(8)