E2IMAGE(8)                (August 2021)                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 recovering catastrophically cor-
          rupted 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 inter-
          vals --- 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 accessible 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 approxi-
          mately 35 Megabytes; a 4 Gigabyte file system with 15,000
          inodes in use out of 550,000 inodes will result in a 3 Mega-
          byte 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 cur-
          rently only supported when creating a raw image file using

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          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 pos-
               sible to clone all and only the used blocks of one file
               system to another device/image file.

          -b superblock
               Get image from partition with broken primary superblock
               by using the superblock located at file system block
               number superblock. The partition is copied as-is
               including broken primary superblock.

          -B blocksize
               Set the file system blocksize in bytes.  Normally,
               e2image will search for the superblock at various dif-
               ferent block sizes in an attempt to find the appropri-
               ate 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 sys-
               tem 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

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          desperation measure when other alternatives have failed.  If
          the file system has changed since the image file was cre-
          ated, data will be lost.  In general, you should make
          another full image backup of the file system 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 sys-
          tem 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

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          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 for your system):

               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 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 cre-
          ated 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 storing 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.

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     OFFSETS
          Normally a file system starts at the beginning of a parti-
          tion, 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
          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@mit.edu).

     AVAILABILITY
          e2image is part of the e2fsprogs package and is available
          from http://e2fsprogs.sourceforge.net.

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

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