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<topic xml:lang="en-us" id="vboxwatchdog-ballonctrl">
  <title>Memory Ballooning Control</title>
  
  <body>
    <p>The memory ballooning control inflates and deflates the memory balloon of VMs based on the VMs free memory and
      the requested maximum balloon size. </p>
    <p>To set up the memory ballooning control the maximum ballooning size a VM can reach needs to be set. This can be
      specified using the command line, as follows: </p>
    <pre xml:space="preserve">--balloon-max &lt;Size in MB&gt;</pre>
    <p>Using a per-VM basis extradata value, as follows: </p>
    <pre xml:space="preserve">VBoxManage setextradata &lt;VM-Name&gt; VBoxInternal2/Watchdog/BalloonCtrl/BalloonSizeMax &lt;Size in MB&gt;</pre>
    <p>Using a global extradata value, as follows: </p>
    <pre xml:space="preserve">VBoxManage setextradata global VBoxInternal2/Watchdog/BalloonCtrl/BalloonSizeMax &lt;Size in MB&gt;</pre>
    <note>
      <p>If no maximum ballooning size is specified by at least one of the parameters above, no ballooning will be
        performed at all. </p>
    </note>
    <p>Setting the ballooning increment in MB can be either done using command line, as follows: </p>
    <pre xml:space="preserve">--balloon-inc &lt;Size in MB&gt;</pre>
    <p>Using a global extradata value, as follows: </p>
    <pre xml:space="preserve">VBoxManage setextradata global VBoxInternal2/Watchdog/BalloonCtrl/BalloonIncrementMB &lt;Size in MB&gt;</pre>
    <p>The default ballooning increment is 256 MB if not specified. </p>
    <p>The same options apply for a ballooning decrement. Using the command line, as follows: </p>
    <pre xml:space="preserve">--balloon-dec &lt;Size in MB&gt;</pre>
    <p>Using a global extradata value, as follows: </p>
    <pre xml:space="preserve">VBoxManage setextradata global VBoxInternal2/Watchdog/BalloonCtrl/BalloonDecrementMB &lt;Size in MB&gt;</pre>
    <p>The default ballooning decrement is 128 MB if not specified. </p>
    <p>The lower limit in MB for a balloon can be defined using the command line, as follows: </p>
    <pre xml:space="preserve">--balloon-lower-limit &lt;Size in MB&gt;</pre>
    <p>Using a global extradata value, as follows: </p>
    <pre xml:space="preserve">VBoxManage setextradata global VBoxInternal2/Watchdog/BalloonCtrl/BalloonLowerLimitMB &lt;Size in MB&gt;</pre>
    <p>The default lower limit is 128 MB if not specified. </p>
  </body>
  
</topic>
