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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 recover‐
       ing 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  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 inter‐
       vals  ---  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 emer‐
       gency situations.

       WARNING!!!!   The -I option should only be used as a desperation measure when other alter‐
       natives 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  compress‐
       ing/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 fol‐
       lows (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 file‐
       names  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.   How‐
       ever,  the -s option will prevent analysis of problems related to hash-tree indexed direc‐
       tories.

       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  minimiz‐
       ing 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 file‐
       names  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.   How‐
       ever,  the -s option will prevent analysis of problems related to hash-tree indexed direc‐
       tories.

       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 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 desir‐
       able 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 parti‐
       tion 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.source‐
       forge.net.

SEE ALSO
       dumpe2fs(8), debugfs(8)

E2fsprogs version 1.42.13                    May 2015                                  E2IMAGE(8)

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