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

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

SYNOPSIS
       e2image	[ -r|-Q	] [ -f ] [ -b superblock ] [ -B	blocksize ] device im-
       age-file
       e2image -I device image-file
       e2image -ra [ -cfnp ] [ -o src_offset ] [ -O  dest_offset  ]  src_fs  [
       dest_fs ]

DESCRIPTION
       The  e2image  program will save critical	ext2, ext3, or ext4 filesystem
       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 filesystems.  In	the future, e2fsck will	be en-
       hanced to be able to use	the image file to help recover a badly damaged
       filesystem.

       When  saving  an	e2image	for debugging purposes,	using either the -r or
       -Q options, the filesystem must be unmounted or be  mounted  read/only,
       in order	for the	image file to be in a consistent state.	 This require-
       ment can	be overridden using the	-f option,  but	 the  resulting	 image
       file is very likely not going to	be useful.

       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.   This  restriction  will
       hopefully be lifted in a	future version of e2image.)

       It  is a	very good idea to create image files for all of	filesystems 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 ev-
       ery week	or so.	The image file should be  stored  on  some  filesystem
       other  than  the	filesystem whose data it contains, to ensure that this
       data is accessible in the case where the	filesystem has been badly dam-
       aged.

       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.  This does not ap-
       ply to the QCOW2	image, which is	not sparse.

       The  size  of  an  ext2 image file depends primarily on the size	of the
       filesystems and how many	inodes are in use.  For	a typical 10  gigabyte
       filesystem,  with  200,000 inodes in use	out of 1.2 million inodes, the
       image file will be approximately	35 megabytes; a	4 gigabyte  filesystem
       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.

RESTORING FILESYSTEM METADATA USING AN IMAGE FILE
       The -I option will cause	e2image	to install the metadata	stored in  the
       image  file back	to the device.	It can be used to restore the filesys-
       tem 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	filesystem has changed
       since the image file was	created, data will be lost.  In	 general,  you
       should  make  a	full image backup of the filesystem first, in case you
       wish to try other recovery strategies afterwards.

RAW IMAGE FILES
       The -r option will create a raw image file instead of  a	 normal	 image
       file.   A  raw image file differs from a	normal image file in two ways.
       First, the filesystem metadata is placed	in the proper position so that
       e2fsck,	dumpe2fs,  debugfs,  etc. can be run directly on the raw image
       file.  In order to minimize the amount of disk space consumed by	a  raw
       image  file,  the file is created as a sparse file.  (Beware of copying
       or compressing/decompressing this file with utilities that don't	under-
       stand  how to create sparse files; the file will	become as large	as the
       filesystem itself!)  Secondly, the raw image file also  includes	 indi-
       rect  blocks  and  directory blocks, which the standard image file does
       not have, although this may change in the future.

       Raw image files are sometimes used  when	 sending  filesystems  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):

	    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 filesystem that the bug reporter may
       wish to keep confidential.  To address this concern, the	-s option  can
       be  specified.	This  will cause e2image to scramble directory entries
       and zero	out any	unused portions	of the directory blocks	before writing
       the  image file.	 However, the -s option	will prevent analysis of prob-
       lems related to hash-tree indexed directories.

       Option -b superblock can	be used	to get image from partition with  bro-
       ken primary superblock.	The partition is copied	as-is including	broken
       primary superblock.

       Option -B blocksize can be used to set superblock block size. Normally,
       e2fsck  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 at a particular blocksize.  If  the  superblock  is  not
       found, e2fsck will terminate with a fatal error.

       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 disk space by	storing	data in	special	format
       with pack data closely together,	hence avoiding holes while still mini-
       mizing size.

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

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

       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 filesystem that the bug reporter may
       wish to keep confidential.  To address this concern, the	-s option  can
       be  specified.	This  will cause e2image to scramble directory entries
       and zero	out any	unused portions	of the directory blocks	before writing
       the  image file.	 However, the -s option	will prevent analysis of prob-
       lems related to hash-tree indexed directories.

       Note that QCOW2 image created by	e2image	is 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.

       Options -b superblock and -B blocksize can be used same way as for  raw
       images.

INCLUDING DATA
       Normally	e2image	only includes fs metadata, not regular file data.  The
       -a option can be	specified to include all data.	This will give an  im-
       age  that  is suitable to use to	clone the entire FS or for backup pur-
       poses.  Note that this option only works	with the raw or	QCOW2 formats.
       The -p switch may be given to show progress.  If	the file system	is be-
       ing 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), the	-c option which	cause e2image to try reading a
       block from the destination to see if it is identical to the block which
       e2image is about	to copy.  If the block is already the same, the	 write
       can  be	skipped.  The -n option	will cause all of the writes to	be no-
       ops, and	print the blocks that would have been written.

OFFSETS
       Normally	a filesystem starts at the beginning of	a partition, and e2im-
       age  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 filesystem starts directly with the -o	option.	 Simi-
       larly the -O option specifies the offset	that should be	seeked	to  in
       the destination before writing the filesystem.

       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  fs
       with:

	    e2image -aro 1048576 img /dev/sda1

       Or you can clone	a fs 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 filesystem 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)

E2fsprogs version 1.45.7	 January 2021			    E2IMAGE(8)

NAME | SYNOPSIS | DESCRIPTION | RESTORING FILESYSTEM METADATA USING AN IMAGE FILE | RAW IMAGE FILES | QCOW2 IMAGE FILES | INCLUDING DATA | OFFSETS | AUTHOR | AVAILABILITY | SEE ALSO

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