misc/e2image.8.in

   1 .\" -*- nroff -*-
   2 .\" Copyright 2001 by Theodore Ts'o.  All Rights Reserved.
   3 .\" This file may be copied under the terms of the GNU Public License.
   4 .\"
   5 .TH E2IMAGE 8 "@E2FSPROGS_MONTH@ @E2FSPROGS_YEAR@" "E2fsprogs version @E2FSPROGS_VERSION@"
   6 .SH NAME
   7 e2image \- Save critical ext2 filesystem data to a file
   8 .SH SYNOPSIS
   9 .B e2image
  10 .I device
  11 .I image-file
  12 .SH DESCRIPTION
  13 The
  14 .B e2image
  15 program will save critical filesystem data on the ext2 filesystem located on
  16 display or change the filesystem label on the ext2 filesystem located on
  17 .I device
  18 to a file specified by
  19 .IR image-file .
  20 The image file may be examined by
  21 .B dumpe2fs
  22 and
  23 .BR  debugfs ,
  24 by using the
  25 .B \-i
  26 option to those programs.  This can be used by an expert in assisting
  27 the recovery of catastrophically corrupted filesystems.  In the future,
  28 e2fsck will be enhanced to be able to use the image file to help
  29 recover a badly damaged filesystem.
  30 .PP
  31 It is a very good idea to periodically (at boot time and
  32 every week or so) to create image files for all of
  33 filesystems on a system, as well as saving the partition
  34 layout (which can be generated using the using
  35 .B fdisk -l
  36 command).  Ideally the image file should be stored on some filesystem
  37 other that
  38 the filesystem whose data it contains, to ensure that its data is
  39 accessible in the case where the filesystem has been badly damaged.
  40 .PP
  41 To save disk space,
  42 .B e2image
  43 creates the image file as a sparse file.
  44 Hence, if the image file
  45 needs to be copied to another location, it should
  46 either be compressed first or copied using the
  47 .B \--sparse=always
  48 option to GNU version of
  49 .BR cp .
  50 .PP
  51 The size of an ext2 image file depends primarily on the size of the
  52 filesystems and how many inodes are in use.  For a typical 10 gigabyte
  53 filesystem, with 200,000 inodes in use out of 1.2 million inodes, the
  54 image file be approximately 35 megabytes; a 4 gigabyte filesystem with
  55 15,000 inodes in use out of 550,000 inodes will result in a 3 megabyte
  56 image file.  Image files tend to be quite
  57 compressible; a sparse image file taking up 32 megabytes of space on
  58 disk will generally compress down to 3 or 4 megabytes.
  59 .PP
  60 .SH AUTHOR
  61 .B e2image
  62 was written by Theodore Ts'o (tytso@mit.edu).
  63 .SH AVAILABILITY
  64 .B e2image
  65 is part of the e2fsprogs package and is available from anonymous
  66 http://e2fsprogs.sourceforge.net.
  67 .SH SEE ALSO
  68 .BR dumpe2fs (8),
  69 .BR debugfs (8)
  70