1E2IMAGE(8) System Manager's Manual E2IMAGE(8)
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6 e2image - Save critical ext2/ext3/ext4 file system metadata to a file
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10 e2image [-r|-Q [-af]] [ -b superblock ] [ -B blocksize ] [ -cnps ] [ -o
11 src_offset ] [ -O dest_offset ] device image-file
12 e2image -I device image-file
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16 The e2image program will save critical ext2, ext3, or ext4 file system
17 metadata located on device to a file specified by image-file. The im‐
18 age file may be examined by dumpe2fs and debugfs, by using the -i op‐
19 tion to those programs. This can assist an expert in recovering cata‐
20 strophically corrupted file systems.
21 It is a very good idea to create image files for all file systems on a
23 system and save the partition layout (which can be generated using the
24 fdisk -l command) at regular intervals --- at boot time, and/or every
25 week or so. The image file should be stored on some file system other
26 than the file system whose data it contains, to ensure that this data
27 is accessible in the case where the file system has been badly damaged.
28 To save disk space, e2image creates the image file as a sparse file, or
30 in QCOW2 format. Hence, if the sparse image file needs to be copied to
31 another location, it should either be compressed first or copied using
32 the --sparse=always option to the GNU version of cp(1). This does not
33 apply to the QCOW2 image, which is not sparse.
34 The size of an ext2 image file depends primarily on the size of the
36 file systems and how many inodes are in use. For a typical 10 Gigabyte
37 file system, with 200,000 inodes in use out of 1.2 million inodes, the
38 image file will be approximately 35 Megabytes; a 4 Gigabyte file system
39 with 15,000 inodes in use out of 550,000 inodes will result in a 3
40 Megabyte image file. Image files tend to be quite compressible; an im‐
41 age file taking up 32 Megabytes of space on disk will generally com‐
42 press down to 3 or 4 Megabytes.
43 If image-file is -, then the output of e2image will be sent to standard
45 output, so that the output can be piped to another program, such as
46 gzip(1). (Note that this is currently only supported when creating a
47 raw image file using the -r option, since the process of creating a
48 normal image file, or QCOW2 image currently requires random access to
49 the file, which cannot be done using a pipe.
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53 -a Include file data in the image file. Normally e2image only in‐
54 cludes fs metadata, not regular file data. This option will
55 produce an image that is suitable to use to clone the entire FS
56 or for backup purposes. Note that this option only works with
57 the raw (-r) or QCOW2 (-Q) formats. In conjunction with the -r
58 option it is possible to clone all and only the used blocks of
59 one file system to another device/image file.
60 -b superblock
62 Get image from partition with broken primary superblock by using
63 the superblock located at file system block number superblock.
64 The partition is copied as-is including broken primary su‐
65 perblock.
66 -B blocksize
68 Set the file system blocksize in bytes. Normally, e2image will
69 search for the superblock at various different block sizes in an
70 attempt to find the appropriate blocksize. This search can be
71 fooled in some cases. This option forces e2fsck to only try lo‐
72 cating the superblock with a particular blocksize. If the su‐
73 perblock is not found, e2image will terminate with a fatal er‐
74 ror.
75 -c Compare each block to be copied from the source device to the
77 corresponding block in the target image-file. If both are al‐
78 ready the same, the write will be skipped. This is useful if
79 the file system is being cloned to a flash-based storage device
80 (where reads are very fast and where it is desirable to avoid
81 unnecessary writes to reduce write wear on the device).
82 -f Override the read-only requirement for the source file system
84 when saving the image file using the -r and -Q options. Nor‐
85 mally, if the source file system is in use, the resulting image
86 file is very likely not going to be useful. In some cases where
87 the source file system is in constant use this may be better
88 than no image at all.
89 -I install the metadata stored in the image file back to the de‐
91 vice. It can be used to restore the file system metadata back
92 to the device in emergency situations.
93 WARNING!!!! The -I option should only be used as a desperation measure
95 when other alternatives have failed. If the file system has changed
96 since the image file was created, data will be lost. In general, you
97 should make another full image backup of the file system first, in case
98 you wish to try other recovery strategies afterward.
99 -n Cause all image writes to be skipped, and instead only print the
101 block numbers that would have been written.
102 -o src_offset
104 Specify offset of the image to be read from the start of the
105 source device in bytes. See OFFSETS for more details.
106 -O tgt_offset
108 Specify offset of the image to be written from the start of the
109 target image-file in bytes. See OFFSETS for more details.
110 -p Show progress of image-file creation.
112 -Q Create a QCOW2-format image file instead of a normal image file,
114 suitable for use by virtual machine images, and other tools that
115 can use the .qcow image format. See QCOW2 IMAGE FILES below for
116 details.
117 -r Create a raw image file instead of a normal image file. See RAW
119 IMAGE FILES below for details.
120 -s Scramble directory entries and zero out unused portions of the
122 directory blocks in the written image file to avoid revealing
123 information about the contents of the file system. However,
124 this will prevent analysis of problems related to hash-tree in‐
125 dexed directories.
126
129 The -r option will create a raw image file, which differs from a normal
130 image file in two ways. First, the file system metadata is placed in
131 the same relative offset within image-file as it is in the device so
132 that debugfs(8), dumpe2fs(8), e2fsck(8), losetup(8), etc. and can be
133 run directly on the raw image file. In order to minimize the amount of
134 disk space consumed by the raw image file, it is created as a sparse
135 file. (Beware of copying or compressing/decompressing this file with
136 utilities that don't understand how to create sparse files; the file
137 will become as large as the file system itself!) Secondly, the raw im‐
138 age file also includes indirect blocks and directory blocks, which the
139 standard image file does not have.
140 Raw image files are sometimes used when sending file systems to the
142 maintainer as part of bug reports to e2fsprogs. When used in this ca‐
143 pacity, the recommended command is as follows (replace hda1 with the
144 appropriate device for your system):
145 e2image -r /dev/hda1 - | bzip2 > hda1.e2i.bz2
147 This will only send the metadata information, without any data blocks.
149 However, the filenames in the directory blocks can still reveal infor‐
150 mation about the contents of the file system that the bug reporter may
151 wish to keep confidential. To address this concern, the -s option can
152 be specified to scramble the filenames in the image.
153 Note that this will work even if you substitute /dev/hda1 for another
155 raw disk image, or QCOW2 image previously created by e2image.
156
159 The -Q option will create a QCOW2 image file instead of a normal, or
160 raw image file. A QCOW2 image contains all the information the raw im‐
161 age does, however unlike the raw image it is not sparse. The QCOW2 im‐
162 age minimize the amount of space used by the image by storing it in
163 special format which packs data closely together, hence avoiding holes
164 while still minimizing size.
165 In order to send file system to the maintainer as a part of bug report
167 to e2fsprogs, use following commands (replace hda1 with the appropriate
168 device for your system):
169 e2image -Q /dev/hda1 hda1.qcow2
171 bzip2 -z hda1.qcow2
172 This will only send the metadata information, without any data blocks.
174 As described for RAW IMAGE FILES the -s option can be specified to
175 scramble the file system names in the image.
176 Note that the QCOW2 image created by e2image is a regular QCOW2 image
178 and can be processed by tools aware of QCOW2 format such as for example
179 qemu-img.
180 You can convert a .qcow2 image into a raw image with:
182 e2image -r hda1.qcow2 hda1.raw
184 This can be useful to write a QCOW2 image containing all data to a
186 sparse image file where it can be loop mounted, or to a disk partition.
187 Note that this may not work with QCOW2 images not generated by e2image.
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191 Normally a file system starts at the beginning of a partition, and
192 e2image is run on the partition. When working with image files, you
193 don't have the option of using the partition device, so you can specify
194 the offset where the file system starts directly with the -o option.
195 Similarly the -O option specifies the offset that should be seeked to
196 in the destination before writing the file system.
197 For example, if you have a dd image of a whole hard drive that contains
199 an ext2 fs in a partition starting at 1 MiB, you can clone that image
200 to a block device with:
201 e2image -aro 1048576 img /dev/sda1
203 Or you can clone a file system from a block device into an image file,
205 leaving room in the first MiB for a partition table with:
206 e2image -arO 1048576 /dev/sda1 img
208 If you specify at least one offset, and only one file, an in-place move
210 will be performed, allowing you to safely move the file system from one
211 offset to another.
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215 e2image was written by Theodore Ts'o (tytso@mit.edu).
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219 e2image is part of the e2fsprogs package and is available from
220 http://e2fsprogs.sourceforge.net.
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224 dumpe2fs(8), debugfs(8) e2fsck(8)
225E2fsprogs version 1.47.0 February 2023 E2IMAGE(8)