Provided by: e2fsprogs_1.42.13-1ubuntu1_i386 bug

NAME

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

SYNOPSIS

       e2image [ -r|Q ] [ -fr ] 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
       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  overriden  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  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 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.  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
       formats.  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)