You must perform certain tasks before you configure a virtual machine to use a physical disk or unused partition on the host system.

You must perform these tasks before you run the New Virtual Machine wizard to add a physical disk to a new virtual machine, and before you add a physical disk to an existing virtual machine.


  1. If a partition is mounted by the host or in use by another virtual machine, unmount it.

    The virtual machine and guest operating system access a physical disk partition while the host continues to run its operating system. Corruption is possible if you allow the virtual machine to modify a partition that is simultaneously mounted on the host operating system.



    The partition is mapped to a Windows Server 2008 R2 or Windows Server 2012 R2 host

    1. Select Start > Settings > Control Panel > Administrative Tools > Computer Management > Storage > Disk Management.

    2. Select a partition and select Action > All Tasks > Change Drive Letter and Paths.

    3. Click Remove.

    The partition is mapped to a Windows 7, Windows 8, or Windows 10 host

    1. Select Start > Control Panel.

    2. In the menu bar, click the arrow next to Control Panel.

    3. From the drop-down menu, select All Control Panel Items > Administrative Tools > Computer Management > Storage > Disk Management (Local).

    4. Right-click a partition and choose Change Drive Letter and Paths.

    5. Click Remove and OK.

  2. Check the guest operating system documentation regarding the type of partition on which the guest operating system can be installed.

    On Windows 7 hosts, you cannot use the system partition, or the physical disk that contains it, in a virtual machine. Other operating systems, such as Linux, can be installed on a primary or an extended partition on any part of the drive.

  3. If the physical partition or disk contains data that you need in the future, back up the data.
  4. If you use a Windows host IDE disk in a physical disk configuration, verify that it is not configured as the slave on the secondary IDE channel if the master on that channel is a CD-ROM drive.
  5. On a Linux host, set the device group membership or device ownership appropriately.
    1. Verify that the master physical disk device or devices are readable and writable by the user who runs Workstation Pro.

      Physical devices, such as /dev/hda (IDE physical disk) and /dev/sdb (SCSI physical disk), belong to group-id disk on most distributions. If this is the case, you can add Workstation Pro users to the disk group. Another option is to change the owner of the device. Consider all the security issues involved in this option.

    2. Grant Workstation Pro users access to all /dev/hd[abcd] physical devices that contain operating systems or boot managers.

      When permissions are set correctly, the physical disk configuration files in Workstation Pro control access. This reliability provides boot managers access to configuration files and other files they might need to boot operating systems. For example, LILO needs to read /boot on a Linux partition to boot a non-Linux operating system that might be on another drive.