Every VM must have a hard disk to which it writes and stores data. The VMware application supports several disk options that provide more flexibility than when using a physical machine.These options fall into the following categories:

• using a virtual disk or a raw disk
• using the three disk modes
• sharing disks by multiple VMs

This chapter describes the advantages of these disk strategies and how to use them.

When you set up a new virtual machine, you must define a hard drive for the VM. Most VMs will use a virtual disk for the hard drive. If you are currently dual-booting your machine, you may decide to use a raw disk. The performance provided by virtual and raw disks is comparable; performance should not be a determinant of which type of disk you use.

Virtual and raw disks are described below.

Most VMs use one or more virtual disks to emulate hard drives. A virtual disk is simply a file created on the host operating system.

You create virtual disks using either the VM configuration wizard or VM configuration editor. You simply provide a file name and size. The VMware application creates the file and subsequently uses it as the hard disk for that VM.

Depending upon the context and whether the emphasis is more disk- or file-related, this manual uses one of two terms: virtual disk or virtual disk file. However, you should keep in mind that both terms refer to an actual file on the host OS.

Virtual disk files can be manipulated by host operating system file system utilities like back up and restore. They are visible to the host OS file system, and you can list their attributes. However, the VMware application is the only process that should write to these files.

If you are currently dual booting your machine, you can define a VM to use a raw disk rather than a virtual disk. A raw disk is a physical disk drive on the physical host machine. During configuration, you can define a raw disk instead of a virtual disk. By using the raw disk, you can then run in a VM the OS that you are currently dual booting from one of the partitions on the disk.

VMware raw disks offer significant advantages over dual booting. While dual booting allows multiple OSs to exist on a machine, they cannot be run simultaneously, and it is tedious to switch between the OSs. In contrast, using raw disks you can work in any number of OSs simultaneously without rebooting. You can transfer data, drag and drop data, or work in one VM while another is processing a large job. You have far more functionality with less bother. You eliminate the tedious switching process and simply move the mouse to the window of the OS that you wish to use. And you can continue to dual boot when that is preferred.

Note

This manual does not describe the implementation or use of raw disks. The current procedure requires careful attention or data can be lost. For more information refer to the VMware Web site.