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

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

SYNOPSIS
       e2image  [-r|-Q [-af]] [ -b superblock ] [ -B blocksize ] [ -cnps ] [ -o src_offset ] [ -O
       dest_offset ] device image-file
       e2image -I device image-file

DESCRIPTION
       The e2image program will save critical ext2, ext3, or ext4 file system 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 file systems.

       It is a very good idea to create image files for all file systems 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 file
       system other than the file system whose data it contains, to ensure that this data is  ac-
       cessible in the case where the file system 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(1).  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 file systems  and  how
       many inodes are in use.  For a typical 10 Gigabyte file system, with 200,000 inodes in use
       out of 1.2 million inodes, the image file will be approximately 35 Megabytes; a 4 Gigabyte
       file  system  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.

       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.

OPTIONS
       -a     Include  file  data in the image file.  Normally e2image only includes fs metadata,
              not regular file data.  This option will produce 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 (-r) or QCOW2 (-Q) formats.  In conjunction with the -r option  it  is
              possible  to  clone  all and only the used blocks of one file system to another de-
              vice/image file.

       -b superblock
              Get image from partition with broken primary superblock by using the superblock lo-
              cated  at  file  system block number superblock.  The partition is copied as-is in-
              cluding broken primary superblock.

       -B blocksize
              Set the file system blocksize in bytes.  Normally, e2image will search for the  su-
              perblock  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 with a particular blocksize. If the superblock is
              not found, e2image will terminate with a fatal error.

       -c     Compare each block to be copied from the source device to the  corresponding  block
              in the target image-file.  If both are already the same, the write will be skipped.
              This is useful 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).

       -f     Override the read-only requirement for the source file system when saving the image
              file  using  the -r and -Q options.  Normally, if the source file system is in use,
              the resulting image file is very likely not going to be useful. In some cases where
              the source file system is in constant use this may be better than no image at all.

       -I     install  the  metadata stored in the image file back to the device.  It can be used
              to restore the file system metadata back to the device in emergency situations.

       WARNING!!!!  The -I option should only be used as a desperation measure when other  alter-
       natives  have  failed.   If  the file system has changed since the image file was created,
       data will be lost.  In general, you should make another full image backup of the file sys-
       tem first, in case you wish to try other recovery strategies afterward.

       -n     Cause all image writes to be skipped, and instead only print the block numbers that
              would have been written.

       -o src_offset
              Specify offset of the image to be read from the  start  of  the  source  device  in
              bytes.  See OFFSETS for more details.

       -O tgt_offset
              Specify  offset  of the image to be written from the start of the target image-file
              in bytes.  See OFFSETS for more details.

       -p     Show progress of image-file creation.

       -Q     Create a QCOW2-format image file instead of a normal image file, suitable  for  use
              by virtual machine images, and other tools that can use the .qcow image format. See
              QCOW2 IMAGE FILES below for details.

       -r     Create a raw image file instead of a normal image file.  See RAW IMAGE FILES  below
              for details.

       -s     Scramble  directory entries and zero out unused portions of the directory blocks in
              the written image file to avoid revealing information about  the  contents  of  the
              file  system.  However, this will prevent analysis of problems related to hash-tree
              indexed directories.

RAW IMAGE FILES
       The -r option will create a raw image file, which differs from a normal image file in  two
       ways.  First, the file system metadata is placed in the same relative offset within image-
       file as it is in the device so that debugfs(8), dumpe2fs(8), e2fsck(8),  losetup(8),  etc.
       and  can  be  run directly on the raw image file.  In order to minimize the amount of disk
       space consumed by the raw image file, it 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 file system itself!)  Secondly, the raw
       image  file  also  includes indirect blocks and directory blocks, which the standard image
       file does not have.

       Raw image files are sometimes used when sending file systems 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 for your system):

            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 file
       system that the bug reporter may wish to keep confidential.  To address this concern,  the
       -s option can be specified to scramble the filenames in the image.

       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 space used by the image by  stor-
       ing  it  in  special  format which packs data closely together, hence avoiding holes while
       still minimizing size.

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

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

       This  will  only send the metadata information, without any data blocks.  As described for
       RAW IMAGE FILES the -s option can be specified to scramble the file system  names  in  the
       image.

       Note that the QCOW2 image created by e2image is a 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.

OFFSETS
       Normally a file system 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 file system starts directly with  the
       -o  option.   Similarly the -O option specifies the offset that should be seeked to in the
       destination before writing the file system.

       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 image to a block device with:

            e2image -aro 1048576 img /dev/sda1

       Or you can clone a file system from a block device 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 file system 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.source-
       forge.net.

SEE ALSO
       dumpe2fs(8), debugfs(8) e2fsck(8)

E2fsprogs version 1.46.5                  December 2021                                E2IMAGE(8)

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