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       qemu-img - QEMU disk image utility


       usage: qemu-img command [command options]


       The following commands are supported:

       check [-f fmt] filename
       create [-f fmt] [-o options] filename [size]
       commit [-f fmt] filename
       convert [-c] [-f fmt] [-O output_fmt] [-o options] filename [filename2
       [...]] output_filename
       info [-f fmt] filename
       snapshot [-l | -a snapshot | -c snapshot | -d snapshot] filename

       Command parameters:

            is a disk image filename

       fmt is the disk image format. It is guessed automatically in most
           cases. See below for a description of the supported disk formats.

           is the disk image size in bytes. Optional suffixes "k" or "K"
           (kilobyte, 1024) "M" (megabyte, 1024k) and "G" (gigabyte, 1024M)
           and T (terabyte, 1024G) are supported.  "b" is ignored.

           is the destination disk image filename

            is the destination format

           is a comma separated list of format specific options in a
           name=value format. Use "-o ?" for an overview of the options
           supported by the used format or see the format descriptions below
           for details.

       -c  indicates that target image must be compressed (qcow format only)

       -h  with or without a command shows help and lists the supported

       Parameters to snapshot subcommand:

           is the name of the snapshot to create, apply or delete

       -a  applies a snapshot (revert disk to saved state)

       -c  creates a snapshot

       -d  deletes a snapshot

       -l  lists all snapshots in the given image

       Command description:

       create [-f fmt] [-o options] filename [size]
           Create the new disk image filename of size size and format fmt.
           Depending on the file format, you can add one or more options that
           enable additional features of this format.

           If the option backing_file is specified, then the image will record
           only the differences from backing_file. No size needs to be
           specified in this case. backing_file will never be modified unless
           you use the "commit" monitor command (or qemu-img commit).

           The size can also be specified using the size option with "-o", it
           doesn't need to be specified separately in this case.

       commit [-f fmt] filename
           Commit the changes recorded in filename in its base image.

       convert [-c] [-f fmt] [-O output_fmt] [-o options] filename [filename2
       [...]] output_filename
           Convert the disk image filename to disk image output_filename using
           format output_fmt. It can be optionally compressed ("-c" option) or
           use any format specific options like encryption ("-o" option).

           Only the formats "qcow" and "qcow2" support compression. The
           compression is read-only. It means that if a compressed sector is
           rewritten, then it is rewritten as uncompressed data.

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

           You can use the backing_file option to force the output image to be
           created as a copy on write image of the specified base image; the
           backing_file should have the same content as the input's base
           image, however the path, image format, etc may differ.

       info [-f fmt] filename
           Give information about the disk image 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.

       snapshot [-l | -a snapshot | -c snapshot | -d snapshot ] filename
           List, apply, create or delete snapshots in image filename.

       Supported image file formats:

       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 holes (for example in ext2 or ext3 on Linux or
           NTFS on Windows), then only the written sectors will reserve space.
           Use "qemu-img info" to know the real size used by the image or "ls
           -ls" on Unix/Linux.

           Host device format. This format should be used instead of raw when
           converting to block devices or other devices where "holes" are not

           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.

           Supported options:

               File name of a base image (see create subcommand)

               Image format of the base image

               If this option is set to "on", the image is encrypted.

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

               Changes the qcow2 cluster size (must be between 512 and 2M).
               Smaller cluster sizes can improve the image file size whereas
               larger cluster sizes generally provide better performance.

               Preallocation mode (allowed values: off, metadata). An image
               with preallocated metadata is initially larger but can improve
               performance when the image needs to grow.

           Old QEMU image format. Left for compatibility.

           Supported options:

               File name of a base image (see create subcommand)

               If this option is set to "on", the image is encrypted.

       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.

       vdi VirtualBox 1.1 compatible image format.

           VMware 3 and 4 compatible image format.

           Supported options:

               Image format of the base image

               Create a VMDK version 6 image (instead of version 4)

       vpc VirtualPC compatible image format (VHD).

           Linux Compressed Loop image, useful only to reuse directly
           compressed CD-ROM images present for example in the Knoppix CD-


       The HTML documentation of QEMU for more precise information and Linux
       user mode emulator invocation.


       Fabrice Bellard

                                  2010-09-06                       QEMU-IMG(1)