2 .\" Copyright 2001 by Theodore Ts'o. All Rights Reserved.
3 .\" This file may be copied under the terms of the GNU Public License.
5 .TH E2IMAGE 8 "@E2FSPROGS_MONTH@ @E2FSPROGS_YEAR@" "E2fsprogs version @E2FSPROGS_VERSION@"
7 e2image \- Save critical ext2/ext3/ext4 filesystem metadata to a file
44 program will save critical ext2, ext3, or ext4 filesystem metadata located on
46 to a file specified by
48 The image file may be examined by
54 option to those programs. This can assist an expert in
55 recovering catastrophically corrupted filesystems. In the future,
56 e2fsck will be enhanced to be able to use the image file to help
57 recover a badly damaged filesystem.
59 When saving an e2image for debugging purposes, using either the
63 options, the filesystem must be unmounted or be mounted read/only, in order
64 for the image file to be in a consistent state. This requirement can be
67 option, but the resulting image file is very likely not going to be useful.
71 is \-, then the output of
73 will be sent to standard output, so that the output can be piped to
74 another program, such as
76 (Note that this is currently only supported when
77 creating a raw image file using the
79 option, since the process of creating a normal image file, or QCOW2
81 requires random access to the file, which cannot be done using a
82 pipe. This restriction will hopefully be lifted in a future version of
85 It is a very good idea to create image files for all of
86 filesystems on a system and save the partition
87 layout (which can be generated using the
89 command) at regular intervals --- at boot time, and/or every week or so.
90 The image file should be stored on some filesystem other than
91 the filesystem whose data it contains, to ensure that this data is
92 accessible in the case where the filesystem has been badly damaged.
96 creates the image file as a sparse file, or in QCOW2 format.
97 Hence, if the sparse image file
98 needs to be copied to another location, it should
99 either be compressed first or copied using the
101 option to the GNU version of
103 This does not apply to the QCOW2 image, which is not sparse.
105 The size of an ext2 image file depends primarily on the size of the
106 filesystems and how many inodes are in use. For a typical 10 gigabyte
107 filesystem, with 200,000 inodes in use out of 1.2 million inodes, the
108 image file will be approximately 35 megabytes; a 4 gigabyte filesystem with
109 15,000 inodes in use out of 550,000 inodes will result in a 3 megabyte
110 image file. Image files tend to be quite
111 compressible; an image file taking up 32 megabytes of space on
112 disk will generally compress down to 3 or 4 megabytes.
114 .SH RESTORING FILESYSTEM METADATA USING AN IMAGE FILE
118 option will cause e2image to install the metadata stored in the image
119 file back to the device. It can be used to restore the filesystem metadata
120 back to the device in emergency situations.
125 option should only be used as a desperation measure when other
126 alternatives have failed. If the filesystem has changed since the image
127 file was created, data
129 be lost. In general, you should make a full image
130 backup of the filesystem first, in case you wish to try other recovery
131 strategies afterwards.
136 option will create a raw image file instead of a normal image file.
137 A raw image file differs
138 from a normal image file in two ways. First, the filesystem metadata is
139 placed in the proper position so that e2fsck, dumpe2fs, debugfs,
140 etc.\& can be run directly on the raw image file. In order to minimize
141 the amount of disk space consumed by a raw image file, the file is
142 created as a sparse file. (Beware of copying or
143 compressing/decompressing this file with utilities that don't understand
144 how to create sparse files; the file will become as large as the
145 filesystem itself!) Secondly, the raw image file also includes indirect
146 blocks and directory blocks, which the standard image file does not have,
147 although this may change in the future.
149 Raw image files are sometimes used when sending filesystems to the maintainer
150 as part of bug reports to e2fsprogs. When used in this capacity, the
151 recommended command is as follows (replace hda1 with the appropriate device):
154 \fBe2image \-r /dev/hda1 \- | bzip2 > hda1.e2i.bz2\fR
156 This will only send the metadata information, without any data blocks.
157 However, the filenames in the directory blocks can still reveal
158 information about the contents of the filesystem that the bug reporter
159 may wish to keep confidential. To address this concern, the
161 option can be specified. This will cause
163 to scramble directory entries and zero out any unused portions
164 of the directory blocks before writing the image file. However,
167 option will prevent analysis of problems related to hash-tree indexed
170 Note that this will work even if you substitute "/dev/hda1" for another raw
171 disk image, or QCOW2 image previously created by
174 .SH QCOW2 IMAGE FILES
177 option will create a QCOW2 image file instead of a normal, or raw image file.
178 A QCOW2 image contains all the information the raw image does, however unlike
179 the raw image it is not sparse. The QCOW2 image minimize the amount of disk
180 space by storing data in special format with pack data closely together, hence
181 avoiding holes while still minimizing size.
183 In order to send filesystem to the maintainer as a part of bug report to
184 e2fsprogs, use following commands (replace hda1 with the appropriate device):
187 \ \fBe2image \-Q /dev/hda1 hda1.qcow2\fR
189 \ \fBbzip2 -z hda1.qcow2\fR
191 This will only send the metadata information, without any data blocks.
192 However, the filenames in the directory blocks can still reveal
193 information about the contents of the filesystem that the bug reporter
194 may wish to keep confidential. To address this concern, the
196 option can be specified. This will cause
198 to scramble directory entries and zero out any unused portions
199 of the directory blocks before writing the image file. However, the
201 option will prevent analysis of problems related to hash-tree indexed
204 Note that QCOW2 image created by
206 is regular QCOW2 image and can be processed by tools aware of QCOW2 format
210 You can convert a qcow2 image into a raw image with:
213 \ \fBe2image \-r hda1.qcow2 hda1.raw\fR
216 This can be useful to write a qcow2 image containing all data to a
217 sparse image file where it can be loop mounted, or to a disk partition.
218 Note that this may not work with qcow2 images not generated by e2image.
223 only includes fs metadata, not regular file data. The
225 option can be specified to include all data. This will
226 give an image that is suitable to use to clone the entire FS or
227 for backup purposes. Note that this option only works with the
228 raw or QCOW2 formats. The
230 switch may be given to show progress. If the file system is being
231 cloned to a flash-based storage device (where reads are very fast and
232 where it is desirable to avoid unnecessary writes to reduce write wear
235 option which cause e2image to try reading a block from the destination
236 to see if it is identical to the block which
238 is about to copy. If the block is already the same, the write can be
241 option will cause all of the writes to be no-ops, and print the blocks
242 that would have been written.
245 Normally a filesystem starts at the beginning of a partition, and
247 is run on the partition. When working with image files, you don't
248 have the option of using the partition device, so you can specify
249 the offset where the filesystem starts directly with the
251 option. Similarly the
253 option specifies the offset that should be seeked to in the destination
254 before writing the filesystem.
256 For example, if you have a
258 image of a whole hard drive that contains an ext2 fs in a partition
259 starting at 1 MiB, you can clone that fs with:
262 \ \fBe2image \-aro 1048576 img /dev/sda1\fR
265 Or you can clone a fs into an image file, leaving room in the first
266 MiB for a partition table with:
269 \ \fBe2image -arO 1048576 /dev/sda1 img\fR
272 If you specify at least one offset, and only one file, an in-place
273 move will be performed, allowing you to safely move the filesystem
274 from one offset to another.
277 was written by Theodore Ts'o (tytso@mit.edu).
280 is part of the e2fsprogs package and is available from
281 http://e2fsprogs.sourceforge.net.