misc/e2image.8.in - platform/external/e2fsprogs_custom - Gitiles

 .\" -*- nroff -*-
 .\" Copyright 2001 by Theodore Ts'o.  All Rights Reserved.
 .\" This file may be copied under the terms of the GNU Public License.
 .\"
 .TH E2IMAGE 8 "@E2FSPROGS_MONTH@ @E2FSPROGS_YEAR@" "E2fsprogs version @E2FSPROGS_VERSION@"
 .SH NAME
 e2image \- Save critical ext2/ext3 filesystem data to a file
 .SH SYNOPSIS
 .B e2image
 [
 .B \-rsI
 ]
 .I device
 .I image-file
 .SH DESCRIPTION
 The
 .B e2image
 program will save critical filesystem data on the ext2 filesystem located on
 .I device
 to a file specified by
 .IR image-file .
 The image file may be examined by
 .B dumpe2fs
 and
 .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,
 e2fsck will be enhanced to be able to use the image file to help
 recover a badly damaged filesystem.
 .PP
 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 is currently only supported when
 creating a raw image file using the
 .B \-r
 option, since the process of creating a normal image file currently
 requires random-access access to the file, which can not 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
 accessible in the case where the filesystem has been badly damaged.
 .PP
 To save disk space,
 .B e2image
 creates the image file as a sparse file.
 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
 .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
 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 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 as part
 of bug reports to e2fsprogs.  When used in this capacity, the
 recommended command is (replace hda1 with 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 them to the image file.
 .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
 http://e2fsprogs.sourceforge.net.
 .SH SEE ALSO
 .BR dumpe2fs (8),
 .BR debugfs (8)
	.\" -- nroff --
	.\" Copyright 2001 by Theodore Ts'o. All Rights Reserved.
	.\" This file may be copied under the terms of the GNU Public License.
	.\"
	.TH E2IMAGE 8 "@E2FSPROGS_MONTH@ @E2FSPROGS_YEAR@" "E2fsprogs version @E2FSPROGS_VERSION@"
	.SH NAME
	e2image \- Save critical ext2/ext3 filesystem data to a file
	.SH SYNOPSIS
	.B e2image
	[
	.B \-rsI
	]
	.I device
	.I image-file
	.SH DESCRIPTION
	The
	.B e2image
	program will save critical filesystem data on the ext2 filesystem located on
	.I device
	to a file specified by
	.IR image-file .
	The image file may be examined by
	.B dumpe2fs
	and
	.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,
	e2fsck will be enhanced to be able to use the image file to help
	recover a badly damaged filesystem.
	.PP
	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 is currently only supported when
	creating a raw image file using the
	.B \-r
	option, since the process of creating a normal image file currently
	requires random-access access to the file, which can not 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
	accessible in the case where the filesystem has been badly damaged.
	.PP
	To save disk space,
	.B e2image
	creates the image file as a sparse file.
	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
	.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
	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 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 as part
	of bug reports to e2fsprogs. When used in this capacity, the
	recommended command is (replace hda1 with 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 them to the image file.
	.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
	http://e2fsprogs.sourceforge.net.
	.SH SEE ALSO
	.BR dumpe2fs (8),
	.BR debugfs (8)