This command creates a new virtual hard disk image. You must specify the filename for the new image and the virtual size. If you give the -static option, disk space for the whole image will be allocated at once on the host. With the -comment option you can attach a comment to the image. The -register option, if given, tells VirtualBox to register the image for use with virtual machines.

You can use the -type option to create a disk in write-through mode, which will not be affected by snapshots; see Sectioná5.2, “Virtual Disk Image (VDI) files” for details. (As described there, you cannot create a VDI with the "immutable" type, as it would then always remain empty.)