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E2IMAGE(8)                                                          E2IMAGE(8)



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

SYNOPSIS
       e2image [ -rsI ] device image-file

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 catastrophically corrupted filesystems.  In the
       future, e2fsck will be enhanced 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 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 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 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  compress-
       ing/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  appropri-
       ate 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.  How-
       ever, 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 previ-
       ously 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 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 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.  How-
       ever, 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.


AUTHOR
       e2image was written by Theodore Ts'o (tytsoATmit.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 1.41.12          May 2010                         E2IMAGE(8)