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 ] device image-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
       image file may be examined by dumpe2fs and debugfs, by using the -i option to those programs.  This can assist an expert in recovering cat-
       astrophically  corrupted filesystems.  In the future, e2fsck will be enhanced to be able to use the image file to help recover a badly dam-
       aged 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 requirement 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 every 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
       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.  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 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 filesys-
       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.

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
       filesystem 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 understand how to create sparse files; the file will become as
       large as the filesystem itself!)  Secondly, the raw image file also includes indirect 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
       capacity, 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
       information  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 problems related to hash-tree indexed directories.

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

       In order to send filesystem to the maintainer as a part of bug report to e2fsprogs, use following commands (replace hda1 with the appropri-
       ate 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
       information  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 problems 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.

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
       image that is suitable to use to clone the entire FS or for backup purposes.  Note that this option only works with the raw or  QCOW2  for-
       mats.   The  -p	switch may be given to show progress.  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), 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 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 filesystem starts directly with the -o option.
       Similarly 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 1.44.1					    March 2018								E2IMAGE(8)