You can add a virtual hard disk to an existing virtual machine, or you can add a hard disk when you customize the virtual machine hardware during the virtual machine creation process. For example, you might need to provide additional disk space for an existing virtual machine with a heavy work load. During virtual machine creation, you might want to add a hard disk that is preconfigured as a boot disk.


  • Verify that you are familiar with configuration options and caveats for adding virtual hard disks. See Virtual Disk Configuration.
  • Before you add disks larger than 2TB in size to a virtual machine, see vSphere Virtual Machine Administration.
  • Verify that you have the Virtual machine.Configuration.Add new disk privilege on the destination folder or datastore.

Power off the virtual machine.


  1. Click Virtual Machines in the VMware Host Client inventory.
  2. Right-click a virtual machine in the list and select Edit settings from the pop-up menu.
  3. (Optional) To delete an existing hard disk, move your pointer over the disk and click the Remove icon (X).
    The disk is removed from the virtual machine. If other virtual machines share the disk, the disk files are not deleted.
  4. On the Virtual Hardware tab, select Add hard disk and select New standard hard disk from the drop-down menu.
    The hard disk appears in the Virtual Hardware devices list.
  5. Expand New Hard disk.
  6. (Optional) Enter a value for the hard disk size and select the units from the drop-down menu.
  7. Select the datastore location where you want to store the virtual machine files.
  8. Select the format for the virtual machine disk.
    Option Description
    Thick Provision Lazy Zeroed

    Create a virtual disk in a default thick format. Space required for the virtual disk is allocated during creation. Any data remaining on the physical device is not erased during creation, but is zeroed out on demand at a later time on first write from the virtual machine.

    Thick Provision Eager Zeroed

    Create a thick disk that supports clustering features such as Fault Tolerance. Space required for the virtual disk is allocated at creation time. In contrast to the flat format, the data remaining on the physical device is zeroed out during creation. It might take much longer to create disks in this format than to create other types of disks.

    Thin Provision

    Use the thin provisioned format. At first, a thin provisioned disk uses only as much datastore space as the disk initially requires. If the thin disk needs more space later, it can grow to the maximum capacity allocated to it.

  9. In the Shares drop-down menu, select a value for the shares to allocate to the virtual disk.
    Shares is a value that represents the relative metric for controlling disk bandwidth. The values Low, Normal, High, and Custom are compared to the sum of all shares of all virtual machines on the host.
  10. If you selected Custom, enter a number of shares in the text box.
  11. In the Limit IOPs box, enter the upper limit of storage resources to allocate to the virtual machine, or select Unlimited.
    This value is the upper limit of I/O operations per second allocated to the virtual disk.
  12. Accept the default or select a different virtual device node.
    In most cases, you can accept the default device node. For a hard disk, using a nondefault device node makes controlling the boot order or having different SCSI controller types easier. For example, you might want to boot from an LSI Logic controller and share a data disk with another virtual machine that is using a Buslogic controller with bus sharing turned on.
  13. (Optional) Select a disk mode.
    Option Description

    Dependent disks are included in snapshots.


    Disks in persistent mode behave like conventional physical computer disks. All data written to a disk in persistent mode are written permanently to the disk.


    Changes to disks in nonpersistent mode are discarded when you power off or reset the virtual machine. The virtual disk returns to the same state every time you restart the virtual machine. Changes to the disk are written to and read from a redo log file that is deleted when you power off or reset.

  14. Click Save.