1E2IMAGE(8)                  System Manager's Manual                 E2IMAGE(8)
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NAME

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

9       e2image [ -r|Q ] [ -f ] device image-file
10       e2image -I device image-file
11       e2image  -ra  [  -cfnp  ] [ -o src_offset ] [ -O dest_offset ] src_fs [
12       dest_fs ]
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DESCRIPTION

15       The e2image program will save critical ext2, ext3, or  ext4  filesystem
16       metadata  located  on  device  to  a file specified by image-file.  The
17       image file may be examined by dumpe2fs and debugfs,  by  using  the  -i
18       option to those programs.  This can assist an expert in recovering cat‐
19       astrophically corrupted filesystems.  In the  future,  e2fsck  will  be
20       enhanced  to be able to use the image file to help recover a badly dam‐
21       aged filesystem.
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23       When saving an e2image for debugging purposes, using either the  -r  or
24       -Q  options,  the filesystem must be unmounted or be mounted read/only,
25       in order for the image file to be in a consistent state.  This require‐
26       ment  can  be  overridden  using the -f option, but the resulting image
27       file is very likely not going to be useful.
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29       If image-file is -, then the output of e2image will be sent to standard
30       output,  so  that  the  output can be piped to another program, such as
31       gzip(1).  (Note that this is currently only supported when  creating  a
32       raw  image  file  using  the -r option, since the process of creating a
33       normal image file, or QCOW2 image currently requires random  access  to
34       the  file,  which  cannot  be done using a pipe.  This restriction will
35       hopefully be lifted in a future version of e2image.)
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37       It is a very good idea to create image files for all of filesystems  on
38       a  system  and  save the partition layout (which can be generated using
39       the fdisk -l command) at regular intervals ---  at  boot  time,  and/or
40       every  week  or so.  The image file should be stored on some filesystem
41       other than the filesystem whose data it contains, to ensure  that  this
42       data is accessible in the case where the filesystem has been badly dam‐
43       aged.
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45       To save disk space, e2image creates the image file as a sparse file, or
46       in QCOW2 format.  Hence, if the sparse image file needs to be copied to
47       another location, it should either be compressed first or copied  using
48       the  --sparse=always  option  to  the GNU version of cp.  This does not
49       apply to the QCOW2 image, which is not sparse.
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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 will be approximately 35 megabytes; a 4 gigabyte filesystem
55       with 15,000 inodes in use out of 550,000 inodes  will  result  in  a  3
56       megabyte  image  file.   Image  files tend to be quite compressible; an
57       image file taking up 32 megabytes of space on disk will generally  com‐
58       press down to 3 or 4 megabytes.
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RESTORING FILESYSTEM METADATA USING AN IMAGE FILE

61       The  -I option will cause e2image to install the metadata stored in the
62       image file back to the device.  It can be used to restore the  filesys‐
63       tem metadata back to the device in emergency situations.
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65       WARNING!!!!  The -I option should only be used as a desperation measure
66       when other alternatives have failed.  If  the  filesystem  has  changed
67       since  the  image file was created, data will be lost.  In general, you
68       should make a full image backup of the filesystem first,  in  case  you
69       wish to try other recovery strategies afterwards.
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RAW IMAGE FILES

72       The  -r  option  will create a raw image file instead of a normal image
73       file.  A raw image file differs from a normal image file in  two  ways.
74       First, the filesystem metadata is placed in the proper position so that
75       e2fsck, dumpe2fs, debugfs, etc. can be run directly on  the  raw  image
76       file.   In order to minimize the amount of disk space consumed by a raw
77       image file, the file is created as a sparse file.  (Beware  of  copying
78       or compressing/decompressing this file with utilities that don't under‐
79       stand how to create sparse files; the file will become as large as  the
80       filesystem  itself!)   Secondly, the raw image file also includes indi‐
81       rect blocks and directory blocks, which the standard  image  file  does
82       not have, although this may change in the future.
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84       Raw  image  files  are  sometimes  used when sending filesystems to the
85       maintainer as part of bug reports to  e2fsprogs.   When  used  in  this
86       capacity,  the recommended command is as follows (replace hda1 with the
87       appropriate device):
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89            e2image -r /dev/hda1 - | bzip2 > hda1.e2i.bz2
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91       This will only send the metadata information, without any data  blocks.
92       However,  the filenames in the directory blocks can still reveal infor‐
93       mation about the contents of the filesystem that the bug  reporter  may
94       wish  to keep confidential.  To address this concern, the -s option can
95       be specified.  This will cause e2image to  scramble  directory  entries
96       and zero out any unused portions of the directory blocks before writing
97       the image file.  However, the -s option will prevent analysis of  prob‐
98       lems related to hash-tree indexed directories.
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100       Note that this will work even if you substitute "/dev/hda1" for another
101       raw disk image, or QCOW2 image previously created by e2image.
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QCOW2 IMAGE FILES

104       The -Q option will create a QCOW2 image file instead of  a  normal,  or
105       raw  image  file.   A  QCOW2 image contains all the information the raw
106       image does, however unlike the raw image it is not  sparse.  The  QCOW2
107       image minimize the amount of disk space by storing data in special for‐
108       mat with pack data closely together, hence avoiding holes  while  still
109       minimizing size.
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111       In  order  to send filesystem to the maintainer as a part of bug report
112       to e2fsprogs, use following commands (replace hda1 with the appropriate
113       device):
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115            e2image -Q /dev/hda1 hda1.qcow2
116            bzip2 -z hda1.qcow2
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118       This  will only send the metadata information, without any data blocks.
119       However, the filenames in the directory blocks can still reveal  infor‐
120       mation  about  the contents of the filesystem that the bug reporter may
121       wish to keep confidential.  To address this concern, the -s option  can
122       be  specified.   This  will cause e2image to scramble directory entries
123       and zero out any unused portions of the directory blocks before writing
124       the  image file.  However, the -s option will prevent analysis of prob‐
125       lems related to hash-tree indexed directories.
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127       Note that QCOW2 image created by e2image is regular QCOW2 image and can
128       be  processed  by tools aware of QCOW2 format such as for example qemu-
129       img.
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131       You can convert a qcow2 image into a raw image with:
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133            e2image -r hda1.qcow2 hda1.raw
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135       This can be useful to write a qcow2 image  containing  all  data  to  a
136       sparse image file where it can be loop mounted, or to a disk partition.
137       Note that this may not work with qcow2 images not generated by e2image.
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INCLUDING DATA

140       Normally e2image only includes fs metadata, not regular file data.  The
141       -a  option  can  be  specified  to include all data.  This will give an
142       image that is suitable to use to clone the entire FS or for backup pur‐
143       poses.  Note that this option only works with the raw or QCOW2 formats.
144       The -p switch may be given to show progress.  If  the  file  system  is
145       being cloned to a flash-based storage device (where reads are very fast
146       and where it is desirable to avoid unnecessary writes to  reduce  write
147       wear on the device), the -c option which cause e2image to try reading a
148       block from the destination to see if it is identical to the block which
149       e2image  is about to copy.  If the block is already the same, the write
150       can be skipped.  The -n option will cause all of the writes to  be  no-
151       ops, and print the blocks that would have been written.
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OFFSETS

154       Normally  a  filesystem  starts  at  the  beginning of a partition, and
155       e2image is run on the partition.  When working with  image  files,  you
156       don't have the option of using the partition device, so you can specify
157       the offset where the filesystem starts directly  with  the  -o  option.
158       Similarly  the  -O option specifies the offset that should be seeked to
159       in the destination before writing the filesystem.
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161       For example, if you have a dd image of a whole hard drive that contains
162       an  ext2  fs  in  a  partition starting at 1 MiB, you can clone that fs
163       with:
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165            e2image -aro 1048576 img /dev/sda1
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167       Or you can clone a fs into an image file, leaving room in the first MiB
168       for a partition table with:
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170            e2image -arO 1048576 /dev/sda1 img
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172       If you specify at least one offset, and only one file, an in-place move
173       will be performed, allowing you to safely move the filesystem from  one
174       offset to another.
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AUTHOR

177       e2image was written by Theodore Ts'o (tytso@mit.edu).
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AVAILABILITY

180       e2image  is  part  of  the  e2fsprogs  package  and  is  available from
181       http://e2fsprogs.sourceforge.net.
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SEE ALSO

184       dumpe2fs(8), debugfs(8)
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189E2fsprogs version 1.44.6          March 2019                        E2IMAGE(8)
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