phpman > man > e2image(8)

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 de‐‐
       bugfs, 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 sys‐
       tem  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 device/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 including
              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 block‐
              size.  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 alterna‐
       tives 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 sys‐
              tem.  However, this will prevent analysis of problems related to hash-tree indexed di‐
              rectories.


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 com‐
       pressing/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 (re‐
       place 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 storing it in spe‐
       cial 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 fol‐
       lowing 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 par‐
       tition.   When working with image files, you don't have the option of using the partition de‐
       vice, 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 be‐
       fore writing the file system.

       For example, if you have a dd image of a whole hard drive that contains an ext2 fs in a  par‐
       tition 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)