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.

During virtual machine creation, a hard disk and a SCSI or SATA controller are added to the virtual machine by default, based on the guest operating system that you select. If this disk does not meet your needs, you can remove it and add a new hard disk at the end of the creation process.

If you add multiple hard disks to a virtual machine, you can assign them to several controllers to improve performance. For controller and bus node behavior, see SCSI and SATA Storage Controller Conditions, Limitations, and Compatibility.



  1. Right-click a virtual machine in the inventory and select Edit Settings.
  2. On the Virtual Hardware tab, add a new hard disk to the virtual machine.
    Client Steps
    vSphere Client Click the Add New Device button and select Hard Disk from the drop-down menu.
    vSphere Web Client
    1. Select New Hard Disk from the New device drop-down menu at the bottom of the wizard.
    2. Click Add.
    The hard disk appears in the Virtual Hardware devices list.
    Note: If the host where the virtual machine resides has available PMem resources, you can place the new hard drive on the host-local PMem datastore.
  3. Expand New hard disk and customize the settings of the new hard disk.
    1. Enter a size for the hard disk and select the unit from the drop-down menu.
    2. From the VM storage policy, select a storage policy or leave the default one.
    3. From the Location drop-down menu, select the datastore location where you want to store virtual machine files.
    4. From the Disk Provisioning drop-down menu, select the format for the hard disk.
      Option Action
      Same format as source Use the same format as the source virtual machine.
      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 thick provision lazy zeroed format, the data remaining on the physical device is zeroed out during creation. It might take 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 needs. If the thin disk needs more space later, it can grow to the maximum capacity allocated to it.
    5. From the Shares drop-down menu, select a value for the shares to allocate to the virtual disk. Alternatively, you can select Custom and enter a value in the text box.
      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.
    6. From the Limit - IOPs drop-down menu, customize 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.
    7. From the Disk Mode drop-down menu, select a disk mode.
      Option Description
      Dependent Dependent disks are included in snapshots.
      Independent - Persistent

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

      Independent - Nonpersistent

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

    8. From the Virtual Device Node, select a virtual device node or leave the default one.

      In most cases, you can accept the default device node. For a hard disk, a nondefault device node is useful to control the boot order or to have different SCSI controller types. 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.