qemu-img.texi

   1 @example
   2 @c man begin SYNOPSIS
   3 usage: qemu-img command [command options]
   4 @c man end
   5 @end example
   6
   7 @c man begin OPTIONS
   8
   9 The following commands are supported:
  10
  11 @include qemu-img-cmds.texi
  12
  13 Command parameters:
  14 @table @var
  15 @item filename
  16  is a disk image filename
  17 @item fmt
  18 is the disk image format. It is guessed automatically in most cases. See below
  19 for a description of the supported disk formats.
  20
  21 @item size
  22 is the disk image size in bytes. Optional suffixes @code{k} or @code{K}
  23 (kilobyte, 1024) @code{M} (megabyte, 1024k) and @code{G} (gigabyte, 1024M)
  24 and T (terabyte, 1024G) are supported.  @code{b} is ignored.
  25
  26 @item output_filename
  27 is the destination disk image filename
  28
  29 @item output_fmt
  30  is the destination format
  31 @item options
  32 is a comma separated list of format specific options in a
  33 name=value format. Use @code{-o ?} for an overview of the options supported
  34 by the used format or see the format descriptions below for details.
  35
  36
  37 @item -c
  38 indicates that target image must be compressed (qcow format only)
  39 @item -h
  40 with or without a command shows help and lists the supported formats
  41 @end table
  42
  43 Parameters to snapshot subcommand:
  44
  45 @table @option
  46
  47 @item snapshot
  48 is the name of the snapshot to create, apply or delete
  49 @item -a
  50 applies a snapshot (revert disk to saved state)
  51 @item -c
  52 creates a snapshot
  53 @item -d
  54 deletes a snapshot
  55 @item -l
  56 lists all snapshots in the given image
  57 @end table
  58
  59 Command description:
  60
  61 @table @option
  62 @item create [-f @var{fmt}] [-o @var{options}] @var{filename} [@var{size}]
  63
  64 Create the new disk image @var{filename} of size @var{size} and format
  65 @var{fmt}. Depending on the file format, you can add one or more @var{options}
  66 that enable additional features of this format.
  67
  68 If the option @var{backing_file} is specified, then the image will record
  69 only the differences from @var{backing_file}. No size needs to be specified in
  70 this case. @var{backing_file} will never be modified unless you use the
  71 @code{commit} monitor command (or qemu-img commit).
  72
  73 The size can also be specified using the @var{size} option with @code{-o},
  74 it doesn't need to be specified separately in this case.
  75
  76 @item commit [-f @var{fmt}] @var{filename}
  77
  78 Commit the changes recorded in @var{filename} in its base image.
  79
  80 @item convert [-c] [-f @var{fmt}] [-O @var{output_fmt}] [-o @var{options}] [-s @var{snapshot_name}] @var{filename} [@var{filename2} [...]] @var{output_filename}
  81
  82 Convert the disk image @var{filename} or a snapshot @var{snapshot_name} to disk image @var{output_filename}
  83 using format @var{output_fmt}. It can be optionally compressed (@code{-c}
  84 option) or use any format specific options like encryption (@code{-o} option).
  85
  86 Only the formats @code{qcow} and @code{qcow2} support compression. The
  87 compression is read-only. It means that if a compressed sector is
  88 rewritten, then it is rewritten as uncompressed data.
  89
  90 Image conversion is also useful to get smaller image when using a
  91 growable format such as @code{qcow} or @code{cow}: the empty sectors
  92 are detected and suppressed from the destination image.
  93
  94 You can use the @var{backing_file} option to force the output image to be
  95 created as a copy on write image of the specified base image; the
  96 @var{backing_file} should have the same content as the input's base image,
  97 however the path, image format, etc may differ.
  98
  99 @item info [-f @var{fmt}] @var{filename}
 100
 101 Give information about the disk image @var{filename}. Use it in
 102 particular to know the size reserved on disk which can be different
 103 from the displayed size. If VM snapshots are stored in the disk image,
 104 they are displayed too.
 105
 106 @item snapshot [-l | -a @var{snapshot} | -c @var{snapshot} | -d @var{snapshot} ] @var{filename}
 107
 108 List, apply, create or delete snapshots in image @var{filename}.
 109
 110 @item resize @var{filename} [+ | -]@var{size}
 111
 112 Change the disk image as if it had been created with @var{size}.
 113
 114 Before using this command to shrink a disk image, you MUST use file system and
 115 partitioning tools inside the VM to reduce allocated file systems and partition
 116 sizes accordingly.  Failure to do so will result in data loss!
 117
 118 After using this command to grow a disk image, you must use file system and
 119 partitioning tools inside the VM to actually begin using the new space on the
 120 device.
 121 @end table
 122
 123 Supported image file formats:
 124
 125 @table @option
 126 @item raw
 127
 128 Raw disk image format (default). This format has the advantage of
 129 being simple and easily exportable to all other emulators. If your
 130 file system supports @emph{holes} (for example in ext2 or ext3 on
 131 Linux or NTFS on Windows), then only the written sectors will reserve
 132 space. Use @code{qemu-img info} to know the real size used by the
 133 image or @code{ls -ls} on Unix/Linux.
 134
 135 @item host_device
 136
 137 Host device format. This format should be used instead of raw when
 138 converting to block devices or other devices where "holes" are not
 139 supported.
 140
 141 @item qcow2
 142 QEMU image format, the most versatile format. Use it to have smaller
 143 images (useful if your filesystem does not supports holes, for example
 144 on Windows), optional AES encryption, zlib based compression and
 145 support of multiple VM snapshots.
 146
 147 Supported options:
 148 @table @code
 149 @item backing_file
 150 File name of a base image (see @option{create} subcommand)
 151 @item backing_fmt
 152 Image format of the base image
 153 @item encryption
 154 If this option is set to @code{on}, the image is encrypted.
 155
 156 Encryption uses the AES format which is very secure (128 bit keys). Use
 157 a long password (16 characters) to get maximum protection.
 158
 159 @item cluster_size
 160 Changes the qcow2 cluster size (must be between 512 and 2M). Smaller cluster
 161 sizes can improve the image file size whereas larger cluster sizes generally
 162 provide better performance.
 163
 164 @item preallocation
 165 Preallocation mode (allowed values: off, metadata). An image with preallocated
 166 metadata is initially larger but can improve performance when the image needs
 167 to grow.
 168
 169 @end table
 170
 171
 172 @item qcow
 173 Old QEMU image format. Left for compatibility.
 174
 175 Supported options:
 176 @table @code
 177 @item backing_file
 178 File name of a base image (see @option{create} subcommand)
 179 @item encryption
 180 If this option is set to @code{on}, the image is encrypted.
 181 @end table
 182
 183 @item cow
 184 User Mode Linux Copy On Write image format. Used to be the only growable
 185 image format in QEMU. It is supported only for compatibility with
 186 previous versions. It does not work on win32.
 187 @item vdi
 188 VirtualBox 1.1 compatible image format.
 189 @item vmdk
 190 VMware 3 and 4 compatible image format.
 191
 192 Supported options:
 193 @table @code
 194 @item backing_fmt
 195 Image format of the base image
 196 @item compat6
 197 Create a VMDK version 6 image (instead of version 4)
 198 @end table
 199
 200 @item vpc
 201 VirtualPC compatible image format (VHD).
 202
 203 @item cloop
 204 Linux Compressed Loop image, useful only to reuse directly compressed
 205 CD-ROM images present for example in the Knoppix CD-ROMs.
 206 @end table
 207
 208
 209 @c man end
 210
 211 @ignore
 212
 213 @setfilename qemu-img
 214 @settitle QEMU disk image utility
 215
 216 @c man begin SEEALSO
 217 The HTML documentation of QEMU for more precise information and Linux
 218 user mode emulator invocation.
 219 @c man end
 220
 221 @c man begin AUTHOR
 222 Fabrice Bellard
 223 @c man end
 224
 225 @end ignore