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<topic xml:lang="en-us" id="ts_win-host-iscsi">
  <title>Running an iSCSI Initiator and Target on a Single System</title>
  
  <body>
    <p>
        Deadlocks can occur on a Windows host when attempting to access
        an iSCSI target running in a guest virtual machine with an iSCSI
        initiator, such as a Microsoft iSCSI Initiator, that is running
        on the host. This is caused by a flaw in the Windows cache
        manager component, and causes sluggish host system response for
        several minutes, followed by a "Delayed Write Failed" error
        message in the system tray or in a separate message window. The
        guest is blocked during that period and may show error messages
        or become unstable.
      </p>
    <p>
        Setting the <codeph>VBOX_DISABLE_HOST_DISK_CACHE</codeph>
        environment variable to <codeph>1</codeph> enables a
        workaround for this problem until Microsoft addresses the issue.
        For example, open a command prompt window and start
        <ph conkeyref="vbox-conkeyref-phrases/product-name"/> like this:
      </p>
    <pre xml:space="preserve">set VBOX_DISABLE_HOST_DISK_CACHE=1
VirtualBox</pre>
    <p>
        While this will decrease guest disk performance, especially
        writes, it does not affect the performance of other applications
        running on the host.
      </p>
  </body>
  
</topic>
