If additional IDE disks are required, it will be necessary to enable the VirtualBox SATA controller for the virtual machine as outlined above and use the SATA IDE compatibility mode. The Secondary Master connection is reserved for CD/DVD devices, allowing for the attachment of three virtual hard disks to the controller. The VirtualBox virtual IDE disk controller allows up to four storage devices to be connected to a virtual machine using the Primary Master, Primary Slave, Secondary Master and Secondary Slave slots. Integrated Drive Electronics (IDE) - Perhaps the most widely used disk controller standard, IDE controllers are now being replaced in favor of the SATA standard.To enable the SATA controller, select the required virtual machine, click on Settings in the toolbar, select Hard Disks from the list of categories and set the Enable SATA Controller check box. The SATA controller is disabled by default for new VirtualBox virtual machines. The first four of these SATA ports are configured by default to operate in IDE compatibility mode. VirtualBox allows up to 30 SATA ports to be configured per virtual machine. SATA disk controllers may be configured to run in IDE compatibility mode to allow access from guest operating systems lacking Advanced Host Controller Interface (AHCI) support.

In addition, SATA is designed to allow disk drives to be added and removed without powering down the system.

Serial ATA (SATA/AHCI) - The latest drive controller standard, SATA provides higher levels of storage access performance and, unlike the older IDE standard, does not impose limited restrictions on the number of devices that can be attached to a single disk controller.

A number of different standards of disk controller have developed over the years and VirtualBox provides virtual versions of the following standards:

Although these virtual controllers are essentially software emulations of physical hard disk controllers, as far as the guest operating systems are concerned, these appear as real, physical devices. VirtualBox provides access to storage by presenting virtual hard disk controllers to virtual machines. 6 Converting a RAW Disk Image to VDI Format.4 Support for Third Party Disk Image Formats.3 Normal, Immutable and Write-Through Disk Images.

1 VirtualBox Virtual Hard Disk Controllers.

Vdi vs vhd vs vmdk