e2image(8) — Linux manual page

NAME | SYNOPSIS | DESCRIPTION | OPTIONS | RAW IMAGE FILES | QCOW2 IMAGE FILES | OFFSETS | AUTHOR | AVAILABILITY | SEE ALSO | COLOPHON

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

NAME         top

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

SYNOPSIS         top

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

DESCRIPTION         top

       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 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 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 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         top

       -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 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 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 alternatives 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
       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         top

       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 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 created by
       e2image.

QCOW2 IMAGE FILES         top

       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.

OFFSETS         top

       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 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         top

       e2image was written by Theodore Ts'o (tytso@mit.edu).

AVAILABILITY         top

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

SEE ALSO         top

       dumpe2fs(8), debugfs(8) e2fsck(8)

COLOPHON         top

       This page is part of the e2fsprogs (utilities for ext2/3/4
       filesystems) project.  Information about the project can be found
       at ⟨http://e2fsprogs.sourceforge.net/⟩.  It is not known how to
       report bugs for this man page; if you know, please send a mail to
       man-pages@man7.org.  This page was obtained from the project's
       upstream Git repository
       ⟨git://git.kernel.org/pub/scm/fs/ext2/e2fsprogs.git⟩ on
       2021-08-27.  (At that time, the date of the most recent commit
       that was found in the repository was 2021-08-22.)  If you
       discover any rendering problems in this HTML version of the page,
       or you believe there is a better or more up-to-date source for
       the page, or you have corrections or improvements to the
       information in this COLOPHON (which is not part of the original
       manual page), send a mail to man-pages@man7.org

E2fsprogs version 1.46.4       August 2021                    E2IMAGE(8)

Pages that refer to this page: e2fsck(8)