The current version of Parallels Workstation creates and uses only virtual hard disks stored in .hdd
files. The size of a virtual disk can be set within the range of 20 MB to 128 GB.
Physical hard disks cannot be used by the current version of Parallels Workstation. To transfer data from the real hard drive to virtual machine use Shared folders or create an image of a real disk with Parallels Image Tool and attach it to the virtual machine as a data disk.
Format of The Virtual Disk
A virtual hard disk can be one of two formats: plain or expanding.
plain |
A disk of this format occupies all of the allocated space from the moment it is created. It takes more space on the real hard disk and more time to create as compared with an expanding virtual hard disk, but allows the guest OS to operate faster. |
expanding |
A disk of this format is small initially and grows as you add applications and data to the Virtual Machine. The disk size you enter when creating the disk is the maximum size to which the disk can grow. When you just begin to operate with the disk, it's size is much less than this value. Expanding disks take less time to create and save disk space. |
Disk format is set when you create a hard disk image. If you need to change the disk format after the hard disk file is created, a copy of the disk in another format can be made using the Parallels Image Tool.
Hard disk images of both formats are stored in .hdd
files, however the structure of a disk file is different. Format of the virtual hard disk is displayed in the Disk format field on the Advanced tab of Hard Disk Options.
If you discover that a hard disk's size is insufficient, you may increase disk capacity using the Parallels Image Tool.
Creating New Virtual Hard Disk
A new virtual hard disk can be created at the same time when a virtual machine is created and attached to this virtual machine. For a typical virtual machine, a new hard disk is created automatically, as for custom virtual machines, you have to select Create a new virtual hard disk option in step 6 of the New Virtual Machine Wizard.
To add a new virtual hard disk to an existing virtual machine use the Add Device Wizard.
You may also replace the current virtual hard disk in an opened virtual machine configuration with a new one using the Recreate button on the Hard Disk Options tab in Configuration Editor.
Besides creating new empty disk, an image of a real hard drive with all the data inside can be created using Parallels Image Tool. This feature is intended mainly for migrating data from real hard drive to virtual machine.
Maintaining Virtual Hard Disks
Virtual hard disks require periodic maintenance procedures to keep disk operations quick and efficient, similarly to real hard disks. An expanding disk is very size efficient at the beginning of a virtual machine's life cycle and becomes less and less efficient as time goes on, because each time writing to the disk is requested, the system allocates new space, and therefore disk size increases. Deleting files does not reduce the size of a virtual disk image file in the primary operating system. Eventually, an expanding virtual disk could grow enormously causing a number of inconveniencies.
Parallels Workstation includes the Disk Compacting Tool which is recommended for all other guest operating systems. For more information on the Disk Compacting Tool refer to the Compacting Virtual Disk topic.