1E2IMAGE(8) System Manager's Manual E2IMAGE(8)
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6 e2image - Save critical ext2/ext3/ext4 filesystem metadata to a file
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9 e2image [ -rsI ] device image-file
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12 The e2image program will save critical ext2, ext3, or ext4 filesystem
13 metadata located on device to a file specified by image-file. The
14 image file may be examined by dumpe2fs and debugfs, by using the -i
15 option to those programs. This can assist an expert in recovering cat‐
16 astrophically corrupted filesystems. In the future, e2fsck will be
17 enhanced to be able to use the image file to help recover a badly dam‐
18 aged filesystem.
19 When saving an e2image for debugging purposes, using either the -r or
21 -Q options, the filesystem must be unmounted or be mounted read/only,
22 in order for the image file to be in a consistent state. This require‐
23 ment can be overridden using the -f option, but the resulting image
24 file is very likely not going to be useful.
25 If image-file is -, then the output of e2image will be sent to standard
27 output, so that the output can be piped to another program, such as
28 gzip(1). (Note that this is currently only supported when creating a
29 raw image file using the -r option, since the process of creating a
30 normal image file, or QCOW2 image currently requires random access to
31 the file, which cannot be done using a pipe. This restriction will
32 hopefully be lifted in a future version of e2image.)
33 It is a very good idea to create image files for all of filesystems on
35 a system and save the partition layout (which can be generated using
36 the fdisk -l command) at regular intervals --- at boot time, and/or
37 every week or so. The image file should be stored on some filesystem
38 other than the filesystem whose data it contains, to ensure that this
39 data is accessible in the case where the filesystem has been badly dam‐
40 aged.
41 To save disk space, e2image creates the image file as a sparse file, or
43 in QCOW2 format. Hence, if the sparse image file needs to be copied to
44 another location, it should either be compressed first or copied using
45 the --sparse=always option to the GNU version of cp. This does not
46 apply to the QCOW2 image, which is not sparse.
47 The size of an ext2 image file depends primarily on the size of the
49 filesystems and how many inodes are in use. For a typical 10 gigabyte
50 filesystem, with 200,000 inodes in use out of 1.2 million inodes, the
51 image file will be approximately 35 megabytes; a 4 gigabyte filesystem
52 with 15,000 inodes in use out of 550,000 inodes will result in a 3
53 megabyte image file. Image files tend to be quite compressible; an
54 image file taking up 32 megabytes of space on disk will generally com‐
55 press down to 3 or 4 megabytes.
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58 The -I option will cause e2image to install the metadata stored in the
59 image file back to the device. It can be used to restore the
60 filesystem metadata back to the device in emergency situations.
61 WARNING!!!! The -I option should only be used as a desperation measure
63 when other alternatives have failed. If the filesystem has changed
64 since the image file was created, data will be lost. In general, you
65 should make a full image backup of the filesystem first, in case you
66 wish to try other recovery strategies afterwards.
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69 The -r option will create a raw image file instead of a normal image
70 file. A raw image file differs from a normal image file in two ways.
71 First, the filesystem metadata is placed in the proper position so that
72 e2fsck, dumpe2fs, debugfs, etc. can be run directly on the raw image
73 file. In order to minimize the amount of disk space consumed by a raw
74 image file, the file is created as a sparse file. (Beware of copying
75 or compressing/decompressing this file with utilities that don't under‐
76 stand how to create sparse files; the file will become as large as the
77 filesystem itself!) Secondly, the raw image file also includes indi‐
78 rect blocks and directory blocks, which the standard image file does
79 not have, although this may change in the future.
80 Raw image files are sometimes used when sending filesystems to the
82 maintainer as part of bug reports to e2fsprogs. When used in this
83 capacity, the recommended command is as follows (replace hda1 with the
84 appropriate device):
85 e2image -r /dev/hda1 - | bzip2 > hda1.e2i.bz2
87 This will only send the metadata information, without any data blocks.
89 However, the filenames in the directory blocks can still reveal infor‐
90 mation about the contents of the filesystem that the bug reporter may
91 wish to keep confidential. To address this concern, the -s option can
92 be specified. This will cause e2image to scramble directory entries
93 and zero out any unused portions of the directory blocks before writing
94 the image file. However, the -s option will prevent analysis of prob‐
95 lems related to hash-tree indexed directories.
96 Note that this will work even if you substitute "/dev/hda1" for another
98 raw disk image, or QCOW2 image previously created by e2image.
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101 The -Q option will create a QCOW2 image file instead of a normal, or
102 raw image file. A QCOW2 image contains all the information the raw
103 image does, however unlike the raw image it is not sparse. The QCOW2
104 image minimize the amount of disk space by storing data in special for‐
105 mat with pack data closely together, hence avoiding holes while still
106 minimizing size.
107 In order to send filesystem to the maintainer as a part of bug report
109 to e2fsprogs, use following commands (replace hda1 with the appropriate
110 device):
111 e2image -Q /dev/hda1 hda1.qcow2
113 bzip2 -z hda1.qcow2
114 This will only send the metadata information, without any data blocks.
116 However, the filenames in the directory blocks can still reveal infor‐
117 mation about the contents of the filesystem that the bug reporter may
118 wish to keep confidential. To address this concern, the -s option can
119 be specified. This will cause e2image to scramble directory entries
120 and zero out any unused portions of the directory blocks before writing
121 the image file. However, the -s option will prevent analysis of prob‐
122 lems related to hash-tree indexed directories.
123 Note that QCOW2 image created by e2image is regular QCOW2 image and can
125 be processed by tools aware of QCOW2 format such as for example qemu-
126 img.
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129 e2image was written by Theodore Ts'o (tytso@mit.edu).
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132 e2image is part of the e2fsprogs package and is available from
133 http://e2fsprogs.sourceforge.net.
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136 dumpe2fs(8), debugfs(8)
137E2fsprogs version 1.41.12 May 2010 E2IMAGE(8)