diff options
Diffstat (limited to 'qemu-img.texi')
| -rw-r--r-- | qemu-img.texi | 70 |
1 files changed, 69 insertions, 1 deletions
diff --git a/qemu-img.texi b/qemu-img.texi index 69f1bda6ae..43ee4eb5c4 100644 --- a/qemu-img.texi +++ b/qemu-img.texi @@ -96,6 +96,14 @@ Second image format Strict mode - fail on on different image size or sector allocation @end table +Parameters to convert subcommand: + +@table @option + +@item -n +Skip the creation of the target volume +@end table + Command description: @table @option @@ -171,7 +179,7 @@ Error on reading data @end table -@item convert [-c] [-p] [-f @var{fmt}] [-t @var{cache}] [-O @var{output_fmt}] [-o @var{options}] [-s @var{snapshot_name}] [-S @var{sparse_size}] @var{filename} [@var{filename2} [...]] @var{output_filename} +@item convert [-c] [-p] [-n] [-f @var{fmt}] [-t @var{cache}] [-O @var{output_fmt}] [-o @var{options}] [-s @var{snapshot_name}] [-S @var{sparse_size}] @var{filename} [@var{filename2} [...]] @var{output_filename} Convert the disk image @var{filename} or a snapshot @var{snapshot_name} to disk image @var{output_filename} using format @var{output_fmt}. It can be optionally compressed (@code{-c} @@ -190,6 +198,11 @@ created as a copy on write image of the specified base image; the @var{backing_file} should have the same content as the input's base image, however the path, image format, etc may differ. +If the @code{-n} option is specified, the target volume creation will be +skipped. This is useful for formats such as @code{rbd} if the target +volume has already been created with site specific options that cannot +be supplied through qemu-img. + @item info [-f @var{fmt}] [--output=@var{ofmt}] [--backing-chain] @var{filename} Give information about the disk image @var{filename}. Use it in @@ -213,6 +226,61 @@ To enumerate information about each disk image in the above chain, starting from qemu-img info --backing-chain snap2.qcow2 @end example +@item map [-f @var{fmt}] [--output=@var{ofmt}] @var{filename} + +Dump the metadata of image @var{filename} and its backing file chain. +In particular, this commands dumps the allocation state of every sector +of @var{filename}, together with the topmost file that allocates it in +the backing file chain. + +Two option formats are possible. The default format (@code{human}) +only dumps known-nonzero areas of the file. Known-zero parts of the +file are omitted altogether, and likewise for parts that are not allocated +throughout the chain. @command{qemu-img} output will identify a file +from where the data can be read, and the offset in the file. Each line +will include four fields, the first three of which are hexadecimal +numbers. For example the first line of: +@example +Offset Length Mapped to File +0 0x20000 0x50000 /tmp/overlay.qcow2 +0x100000 0x10000 0x95380000 /tmp/backing.qcow2 +@end example +@noindent +means that 0x20000 (131072) bytes starting at offset 0 in the image are +available in /tmp/overlay.qcow2 (opened in @code{raw} format) starting +at offset 0x50000 (327680). Data that is compressed, encrypted, or +otherwise not available in raw format will cause an error if @code{human} +format is in use. Note that file names can include newlines, thus it is +not safe to parse this output format in scripts. + +The alternative format @code{json} will return an array of dictionaries +in JSON format. It will include similar information in +the @code{start}, @code{length}, @code{offset} fields; +it will also include other more specific information: +@itemize @minus +@item +whether the sectors contain actual data or not (boolean field @code{data}; +if false, the sectors are either unallocated or stored as optimized +all-zero clusters); + +@item +whether the data is known to read as zero (boolean field @code{zero}); + +@item +in order to make the output shorter, the target file is expressed as +a @code{depth}; for example, a depth of 2 refers to the backing file +of the backing file of @var{filename}. +@end itemize + +In JSON format, the @code{offset} field is optional; it is absent in +cases where @code{human} format would omit the entry or exit with an error. +If @code{data} is false and the @code{offset} field is present, the +corresponding sectors in the file are not yet in use, but they are +preallocated. + +For more information, consult @file{include/block/block.h} in QEMU's +source code. + @item snapshot [-l | -a @var{snapshot} | -c @var{snapshot} | -d @var{snapshot} ] @var{filename} List, apply, create or delete snapshots in image @var{filename}. |