![aliguori](/assets/img/avatar_default.png)
If the user specifies the backing file format, then when opening the backing file, there is no need to probe the (backing file) image to figure out its format. This follows my previous patches implementing bdrv_create2 which keeps (for qcow2 only) the backing file format as a qcow2-extension Suggested by Daniel P. Berrange. Signed-off-by: Uri Lublin <uril@redhat.com> Signed-off-by: Anthony Liguori <aliguori@us.ibm.com> git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@6910 c046a42c-6fe2-441c-8c8c-71466251a162
163 lines
5.3 KiB
Text
163 lines
5.3 KiB
Text
@example
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@c man begin SYNOPSIS
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usage: qemu-img command [command options]
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@c man end
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@end example
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@c man begin OPTIONS
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The following commands are supported:
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@table @option
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@item create [-e] [-6] [-F @var{base_fmt}] [-b @var{base_image}] [-f @var{fmt}] @var{filename} [@var{size}]
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@item commit [-f @var{fmt}] @var{filename}
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@item convert [-c] [-e] [-6] [-f @var{fmt}] [-O @var{output_fmt}] [-B @var{output_base_image}] @var{filename} [@var{filename2} [...]] @var{output_filename}
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@item info [-f @var{fmt}] @var{filename}
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@item snapshot [-l | -a @var{snapshot} | -c @var{snapshot} | -d @var{snapshot}] @var{filename}
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@end table
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Command parameters:
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@table @var
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@item filename
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is a disk image filename
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@item base_image
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is the read-only disk image which is used as base for a copy on
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write image; the copy on write image only stores the modified data
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@item output_base_image
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forces the output image to be created as a copy on write
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image of the specified base image; @code{output_base_image} should have the same
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content as the input's base image, however the path, image format, etc may
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differ
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@item base_fmt
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is the disk image format of @var{base_image}. for more information look at @var{fmt}
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@item fmt
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is the disk image format. It is guessed automatically in most cases. The following formats are supported:
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@table @code
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@item raw
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Raw disk image format (default). This format has the advantage of
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being simple and easily exportable to all other emulators. If your
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file system supports @emph{holes} (for example in ext2 or ext3 on
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Linux or NTFS on Windows), then only the written sectors will reserve
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space. Use @code{qemu-img info} to know the real size used by the
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image or @code{ls -ls} on Unix/Linux.
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@item qcow2
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QEMU image format, the most versatile format. Use it to have smaller
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images (useful if your filesystem does not supports holes, for example
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on Windows), optional AES encryption, zlib based compression and
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support of multiple VM snapshots.
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@item qcow
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Old QEMU image format. Left for compatibility.
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@item cow
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User Mode Linux Copy On Write image format. Used to be the only growable
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image format in QEMU. It is supported only for compatibility with
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previous versions. It does not work on win32.
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@item vmdk
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VMware 3 and 4 compatible image format.
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@item cloop
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Linux Compressed Loop image, useful only to reuse directly compressed
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CD-ROM images present for example in the Knoppix CD-ROMs.
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@end table
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@item size
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is the disk image size in kilobytes. Optional suffixes @code{M}
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(megabyte, 1024 * 1024) and @code{G} (gigabyte, 1024 * 1024 * 1024)
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are supported and any @code{k} or @code{K} is ignored.
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@item output_filename
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is the destination disk image filename
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@item output_fmt
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is the destination format
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@item -c
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indicates that target image must be compressed (qcow format only)
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@item -e
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indicates that the target image must be encrypted (qcow format only)
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@item -6
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indicates that the target image must use compatibility level 6 (vmdk format only)
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@item -h
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with or without a command shows help and lists the supported formats
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@end table
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Parameters to snapshot subcommand:
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@table @option
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@item snapshot
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is the name of the snapshot to create, apply or delete
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@item -a
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applies a snapshot (revert disk to saved state)
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@item -c
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creates a snapshot
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@item -d
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deletes a snapshot
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@item -l
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lists all snapshots in the given image
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@end table
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Command description:
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@table @option
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@item create [-6] [-e] [-b @var{base_image}] [-f @var{fmt}] @var{filename} [@var{size}]
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Create the new disk image @var{filename} of size @var{size} and format
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@var{fmt}.
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If @var{base_image} is specified, then the image will record only the
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differences from @var{base_image}. No size needs to be specified in
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this case. @var{base_image} will never be modified unless you use the
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@code{commit} monitor command.
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@item commit [-f @var{fmt}] @var{filename}
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Commit the changes recorded in @var{filename} in its base image.
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@item convert [-c] [-e] [-f @var{fmt}] @var{filename} [-O @var{output_fmt}] @var{output_filename}
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Convert the disk image @var{filename} to disk image @var{output_filename}
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using format @var{output_fmt}. It can be optionally encrypted
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(@code{-e} option) or compressed (@code{-c} option).
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Only the format @code{qcow} supports encryption or compression. The
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compression is read-only. It means that if a compressed sector is
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rewritten, then it is rewritten as uncompressed data.
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Encryption uses the AES format which is very secure (128 bit keys). Use
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a long password (16 characters) to get maximum protection.
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Image conversion is also useful to get smaller image when using a
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growable format such as @code{qcow} or @code{cow}: the empty sectors
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are detected and suppressed from the destination image.
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@item info [-f @var{fmt}] @var{filename}
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Give information about the disk image @var{filename}. Use it in
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particular to know the size reserved on disk which can be different
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from the displayed size. If VM snapshots are stored in the disk image,
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they are displayed too.
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@item snapshot [-l | -a @var{snapshot} | -c @var{snapshot} | -d @var{snapshot} ] @var{filename}
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List, apply, create or delete snapshots in image @var{filename}.
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@end table
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@c man end
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@ignore
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@setfilename qemu-img
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@settitle QEMU disk image utility
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@c man begin SEEALSO
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The HTML documentation of QEMU for more precise information and Linux
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user mode emulator invocation.
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@c man end
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@c man begin AUTHOR
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Fabrice Bellard
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@c man end
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@end ignore
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