.\"
.TH E2IMAGE 8 "@E2FSPROGS_MONTH@ @E2FSPROGS_YEAR@" "E2fsprogs version @E2FSPROGS_VERSION@"
.SH NAME
-e2image \- Save critical ext2/ext3 filesystem data to a file
+e2image \- Save critical ext2/ext3/ext4 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
+program will save critical ext2, ext3, or ext4 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
If
.I image-file
-is -, then the output of
+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
+(Note that this 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
+option, since the process of creating a normal image file, or QCOW2
+image 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 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,
+.B e2image
+creates the image file as a sparse file, or in QCOW2 format.
+Hence, if the sparse image file
+needs to be copied to another location, it should
+either be compressed first or copied using the
+.B \-\-sparse=always
+option to the GNU version of
+.BR cp .
+This does not apply to the QCOW2 image, which is not sparse.
+.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 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.
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,
+blocks and directory blocks, which the standard image file does not have,
although this may change in the future.
.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.
+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
-To save disk space,
+.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
+Note that this will work even if you substitute "/dev/hda1" for another raw
+disk image, or QCOW2 image previously created by
+.BR e2image .
+.PP
+.SH QCOW2 IMAGE FILES
+The
+.B \-Q
+option will create a QCOW2 image file instead of a normal, or raw image file.
+A QCOW2 image contains all the information the raw image does, however unlike
+the raw image it is not sparse. The QCOW2 image minimize the amount of disk
+space by storing data in special format with pack data closely together, hence
+avoiding holes while still minimizing size.
+.PP
+In order to send filesystem to the maintainer as a part of bug report to
+e2fsprogs, use following commands (replace hda1 with the appropriate device):
+.PP
+.br
+\ \fBe2image \-Q /dev/hda1 hda1.qcow2\fR
+.br
+\ \fBbzip2 -z hda1.qcow2\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
-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 .
+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
-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.
+Note that QCOW2 image created by
+.B e2image
+is regular QCOW2 image and can be processed by tools aware of QCOW2 format
+such as for example
+.BR qemu-img .
.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