.\"
.TH E2IMAGE 8 "@E2FSPROGS_MONTH@ @E2FSPROGS_YEAR@" "E2fsprogs version @E2FSPROGS_VERSION@"
.SH NAME
-e2image \- Save critical ext2 filesystem data to a file
+e2image \- Save critical ext2/ext3 filesystem metadata to a file
.SH SYNOPSIS
.B e2image
[
-.B \-r
+.B \-rsI
]
.I device
.I image-file
.SH DESCRIPTION
The
.B e2image
-program will save critical filesystem data on the ext2 filesystem located on
-display or change the filesystem label on the ext2 filesystem located on
+program will save critical ext2 or ext3 filesystem metadata located on
.I device
to a file specified by
.IR image-file .
.BR debugfs ,
by using the
.B \-i
-option to those programs. This can be used by an expert in assisting
-the recovery of catastrophically corrupted filesystems. In the future,
+option to those programs. This can assist an expert in
+recovering catastrophically corrupted filesystems. In the future,
e2fsck will be enhanced to be able to use the image file to help
recover a badly damaged filesystem.
.PP
-The
+If
+.I image-file
+is \-, then the output of
+.B e2image
+will be sent to standard output, so that the output can be piped to
+another program, such as
+.BR gzip (1).
+(Note that this is currently only supported when
+creating a raw image file using the
.B \-r
-option will create a raw image file instead. A raw image file differs
-from a normal image file in two ways. First, the filesystem metadata is
-placed in the proper position so that e2fsck, dumpe2fs, debugfs,
-etc. can be run directly on the raw image file. In order to minimize
-the amount of disk space consumed by a raw image file, the file is
-created as a sparse file. (Beware of copying or
-compressing/decompressing this file with utilities that don't understand
-how to create sparse files; the file will become as large as the
-filesystem itself!) Secondly, the raw image file also includes indirect
-blocks and data blocks, which the current image file does not have ---
-although this may change in the future.
+option, since the process of creating a normal image file currently
+requires random access to the file, which cannot be done using a
+pipe. This restriction will hopefully be lifted in a future version of
+.BR e2image .)
.PP
-It is a very good idea to periodically (at boot time and
-every week or so) to create image files for all of
-filesystems on a system, as well as saving the partition
-layout (which can be generated using the using
-.B fdisk -l
-command). Ideally the image file should be stored on some filesystem
-other that
-the filesystem whose data it contains, to ensure that its data is
+It is a very good idea to create image files for all of
+filesystems on a system and save the partition
+layout (which can be generated using the
+.B fdisk \-l
+command) at regular intervals --- at boot time, and/or every week or so.
+The image file should be stored on some filesystem other than
+the filesystem whose data it contains, to ensure that this data is
accessible in the case where the filesystem has been badly damaged.
.PP
To save disk space,
Hence, if the image file
needs to be copied to another location, it should
either be compressed first or copied using the
-.B \--sparse=always
-option to GNU version of
+.B \-\-sparse=always
+option to the GNU version of
.BR cp .
.PP
The size of an ext2 image file depends primarily on the size of the
filesystems and how many inodes are in use. For a typical 10 gigabyte
filesystem, with 200,000 inodes in use out of 1.2 million inodes, the
-image file be approximately 35 megabytes; a 4 gigabyte filesystem with
+image file will be approximately 35 megabytes; a 4 gigabyte filesystem with
15,000 inodes in use out of 550,000 inodes will result in a 3 megabyte
image file. Image files tend to be quite
compressible; an image file taking up 32 megabytes of space on
disk will generally compress down to 3 or 4 megabytes.
.PP
+.SH RESTORING FILESYSTEM METADATA USING AN IMAGE FILE
+.PP
+The
+.B \-I
+option will cause e2image to install the metadata stored in the image
+file back to the device. It can be used to restore the filesystem metadata
+back to the device in emergency situations.
+.PP
+.B WARNING!!!!
+The
+.B \-I
+option should only be used as a desperation measure when other
+alternatives have failed. If the filesystem has changed since the image
+file was created, data
+.B will
+be lost. In general, you should make a full image
+backup of the filesystem first, in case you wish to try other recovery
+strategies afterwards.
+.PP
+.SH RAW IMAGE FILES
+The
+.B \-r
+option will create a raw image file instead of a normal image file.
+A raw image file differs
+from a normal image file in two ways. First, the filesystem metadata is
+placed in the proper position so that e2fsck, dumpe2fs, debugfs,
+etc. can be run directly on the raw image file. In order to minimize
+the amount of disk space consumed by a raw image file, the file is
+created as a sparse file. (Beware of copying or
+compressing/decompressing this file with utilities that don't understand
+how to create sparse files; the file will become as large as the
+filesystem itself!) Secondly, the raw image file also includes indirect
+blocks and directory blocks, which the standard image file does not have,
+although this may change in the future.
+.PP
+Raw image files are sometimes used when sending filesystems to the maintainer
+as part of bug reports to e2fsprogs. When used in this capacity, the
+recommended command is as follows (replace hda1 with the appropriate device):
+.PP
+.br
+\ \fBe2image \-r /dev/hda1 \- | bzip2 > hda1.e2i.bz2\fR
+.PP
+This will only send the metadata information, without any data blocks.
+However, the filenames in the directory blocks can still reveal
+information about the contents of the filesystem that the bug reporter
+may wish to keep confidential. To address this concern, the
+.B \-s
+option can be specified. This will cause
+.B e2image
+to scramble directory entries and zero out any unused portions
+of the directory blocks before writing the image file. However,
+the
+.B \-s
+option will prevent analysis of problems related to hash-tree indexed
+directories.
+.PP
.SH AUTHOR
.B e2image
was written by Theodore Ts'o (tytso@mit.edu).
.SH AVAILABILITY
.B e2image
-is part of the e2fsprogs package and is available from anonymous
+is part of the e2fsprogs package and is available from
http://e2fsprogs.sourceforge.net.
.SH SEE ALSO
.BR dumpe2fs (8),
git://git.whamcloud.com / tools / e2fsprogs.git / blobdiff