You can create a virtual disk, use an existing virtual disk, or create Raw Device Mappings (RDMs), which give your virtual disk direct access to SAN. A virtual disk comprises one or more files on the file system that appear as a single hard disk to the guest operating system. These disks are portable among hosts.

You can add virtual disks to the virtual machine while you create or after you create the virtual machine. To add disks later, select the Do Not Create Disk option.

You can select from the following options:

When you create a virtual disk, you can specify disk properties such as size, format, clustering features, and more.

You can use an existing disk that is configured with an operating system or other virtual machine data. This choice allows you to freely move the virtual hard drive from virtual machine to virtual machine.

For virtual machines running on an ESX/ESXi host, instead of storing virtual machine data in a virtual disk file, you can store the data directly on a SAN LUN. This is useful if you are running applications in your virtual machines that must know the physical characteristics of the storage device. Additionally, mapping a SAN LUN allows you to use existing SAN commands to manage storage for the disk.