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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 im-
       age file	may be examined	by dumpe2fs and	debugfs, by using the  -i  op-
       tion  to	those programs.	 This can assist an expert in recovering cata-
       strophically 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 im-
       age  file  taking  up 32	Megabytes of space on disk will	generally com-
       press 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 in-
	      cludes 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 su-
	      perblock.

       -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 lo-
	      cating the superblock with a particular blocksize.  If  the  su-
	      perblock	is  not	found, e2image will terminate with a fatal er-
	      ror.

       -c     Compare each block to be copied from the source  device  to  the
	      corresponding  block  in the target image-file.  If both are al-
	      ready 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.	  Nor-
	      mally,  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  de-
	      vice.   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  in-
	      dexed 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 im-
       age 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  ca-
       pacity,	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	infor-
       mation 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 im-
       age  does, however unlike the raw image it is not sparse. The QCOW2 im-
       age 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
       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
       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)

E2fsprogs version 1.46.4	  August 2021			    E2IMAGE(8)

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

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