File:  [Qemu by Fabrice Bellard] / qemu / qemu-img.texi
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Tue Apr 24 16:51:01 2018 UTC (3 years ago) by root
Branches: qemu, MAIN
CVS tags: qemu0105, qemu0104, qemu0103, qemu0102, qemu0101, qemu0100, HEAD
qemu 0.10.0

@c man begin SYNOPSIS
usage: qemu-img command [command options]
@c man end
@end example

@c man begin OPTIONS

The following commands are supported:
@table @option
@item create [-e] [-6] [-b @var{base_image}] [-f @var{fmt}] @var{filename} [@var{size}]
@item commit [-f @var{fmt}] @var{filename}
@item convert [-c] [-e] [-6] [-f @var{fmt}] [-O @var{output_fmt}] [-B @var{output_base_image}] @var{filename} [@var{filename2} [...]] @var{output_filename}
@item info [-f @var{fmt}] @var{filename}
@item snapshot [-l | -a @var{snapshot} | -c @var{snapshot} | -d @var{snapshot}] @var{filename}
@end table

Command parameters:
@table @var
@item filename
 is a disk image filename
@item base_image
is the read-only disk image which is used as base for a copy on
    write image; the copy on write image only stores the modified data
@item output_base_image
forces the output image to be created as a copy on write
image of the specified base image; @code{output_base_image} should have the same
content as the input's base image, however the path, image format, etc may
@item fmt
is the disk image format. It is guessed automatically in most cases. The following formats are supported:

@table @code
@item raw

Raw disk image format (default). This format has the advantage of
being simple and easily exportable to all other emulators. If your
file system supports @emph{holes} (for example in ext2 or ext3 on
Linux or NTFS on Windows), then only the written sectors will reserve
space. Use @code{qemu-img info} to know the real size used by the
image or @code{ls -ls} on Unix/Linux.

@item qcow2
QEMU image format, the most versatile format. Use it to have smaller
images (useful if your filesystem does not supports holes, for example
on Windows), optional AES encryption, zlib based compression and
support of multiple VM snapshots.
@item qcow
Old QEMU image format. Left for compatibility.
@item cow
User Mode Linux Copy On Write image format. Used to be the only growable
image format in QEMU. It is supported only for compatibility with
previous versions. It does not work on win32.
@item vmdk
VMware 3 and 4 compatible image format.
@item cloop
Linux Compressed Loop image, useful only to reuse directly compressed
CD-ROM images present for example in the Knoppix CD-ROMs.
@end table

@item size
is the disk image size in kilobytes. Optional suffixes @code{M}
(megabyte, 1024 * 1024) and @code{G} (gigabyte, 1024 * 1024 * 1024)
are supported and any @code{k} or @code{K} is ignored.

@item output_filename
is the destination disk image filename

@item output_fmt
 is the destination format

@item -c
indicates that target image must be compressed (qcow format only)
@item -e
indicates that the target image must be encrypted (qcow format only)
@item -6
indicates that the target image must use compatibility level 6 (vmdk format only)
@item -h
with or without a command shows help and lists the supported formats
@end table

Parameters to snapshot subcommand:

@table @option

@item snapshot
is the name of the snapshot to create, apply or delete
@item -a
applies a snapshot (revert disk to saved state)
@item -c
creates a snapshot
@item -d
deletes a snapshot
@item -l
lists all snapshots in the given image
@end table

Command description:

@table @option
@item create [-6] [-e] [-b @var{base_image}] [-f @var{fmt}] @var{filename} [@var{size}]

Create the new disk image @var{filename} of size @var{size} and format

If @var{base_image} is specified, then the image will record only the
differences from @var{base_image}. No size needs to be specified in
this case. @var{base_image} will never be modified unless you use the
@code{commit} monitor command.

@item commit [-f @var{fmt}] @var{filename}

Commit the changes recorded in @var{filename} in its base image.

@item convert [-c] [-e] [-f @var{fmt}] @var{filename} [-O @var{output_fmt}] @var{output_filename}

Convert the disk image @var{filename} to disk image @var{output_filename}
using format @var{output_fmt}. It can be optionally encrypted
(@code{-e} option) or compressed (@code{-c} option).

Only the format @code{qcow} supports encryption or compression. The
compression is read-only. It means that if a compressed sector is
rewritten, then it is rewritten as uncompressed data.

Encryption uses the AES format which is very secure (128 bit keys). Use
a long password (16 characters) to get maximum protection.

Image conversion is also useful to get smaller image when using a
growable format such as @code{qcow} or @code{cow}: the empty sectors
are detected and suppressed from the destination image.

@item info [-f @var{fmt}] @var{filename}

Give information about the disk image @var{filename}. Use it in
particular to know the size reserved on disk which can be different
from the displayed size. If VM snapshots are stored in the disk image,
they are displayed too.

@item snapshot [-l | -a @var{snapshot} | -c @var{snapshot} | -d @var{snapshot} ] @var{filename}

List, apply, create or delete snapshots in image @var{filename}.
@end table

@c man end


@setfilename qemu-img
@settitle QEMU disk image utility

@c man begin SEEALSO
The HTML documentation of QEMU for more precise information and Linux
user mode emulator invocation.
@c man end

@c man begin AUTHOR
Fabrice Bellard
@c man end

@end ignore