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1 perry 1 E2IMAGE
2 !!!E2IMAGE
3 NAME
4 SYNOPSIS
5 DESCRIPTION
6 AUTHOR
7 AVAILABILITY
8 SEE ALSO
9 ----
10 !!NAME
11
12
13 e2image - Save critical ext2 filesystem data to a file
14 !!SYNOPSIS
15
16
17 __e2image__ [[ __-r__ ] ''device
18 image-file''
19 !!DESCRIPTION
20
21
22 The __e2image__ program will save critical filesystem
23 data on the ext2 filesystem located on ''device'' to a
24 file specified by ''image-file''. The image file may be
25 examined by __dumpe2fs__ and __debugfs__, by using the
26 __-i__ option to those programs. This can be used by an
27 expert in assisting the recovery of catastrophically
28 corrupted filesystems. In the future, e2fsck will be
29 enhanced to be able to use the image file to help recover a
30 badly damaged filesystem.
31
32
33 If ''image-file'' is -, then the output of __e2image__
34 will be sent to standard output.
35
36
37 The __-r__ option will create a raw image file instead of
38 a normal image file. A raw image file differs from a normal
39 image file in two ways. First, the filesystem metadata is
40 placed in the proper position so that e2fsck, dumpe2fs,
41 debugfs, etc. can be run directly on the raw image file. In
42 order to minimize the amount of disk space consumed by a raw
43 image file, the file is created as a sparse file. (Beware of
44 copying or compressing/decompressing this file with
45 utilities that don't understand how to create sparse files;
46 the file will become as large as the filesystem itself!)
47 Secondly, the raw image file also includes indirect blocks
48 and data blocks, which the current image file does not have,
49 although this may change in the future.
50
51
52 It is a very good idea to periodically (at boot time and
53 every week or so) to create image files for all of
54 filesystems on a system, as well as saving the partition
55 layout (which can be generated using the using __fdisk
56 -l__ command). Ideally the image file should be stored on
57 some filesystem other that the filesystem whose data it
58 contains, to ensure that its data is accessible in the case
59 where the filesystem has been badly damaged.
60
61
62 To save disk space, __e2image__ creates the image file as
63 a sparse file. Hence, if the image file needs to be copied
64 to another location, it should either be compressed first or
65 copied using the __--sparse=always__ option to GNU
66 version of __cp__.
67
68
69 The size of an ext2 image file depends primarily on the size
70 of the filesystems and how many inodes are in use. For a
71 typical 10 gigabyte filesystem, with 200,000 inodes in use
72 out of 1.2 million inodes, the image file be approximately
73 35 megabytes; a 4 gigabyte filesystem with 15,000 inodes in
74 use out of 550,000 inodes will result in a 3 megabyte image
75 file. Image files tend to be quite compressible; an image
76 file taking up 32 megabytes of space on disk will generally
77 compress down to 3 or 4 megabytes.
78 !!AUTHOR
79
80
81 __e2image__ was written by Theodore Ts'o
82 (tytso@mit.edu).
83 !!AVAILABILITY
84
85
86 __e2image__ is part of the e2fsprogs package and is
87 available from anonymous
88 http://e2fsprogs.sourceforge.net.
89 !!SEE ALSO
90
91
2 perry 92 dumpe2fs(8), debugfs(8)
1 perry 93 ----
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