5 Virtual storage The known media are conveniently grouped in three tabs for the three possible formats. These formats are: • Hard disk images, either in VirtualBox’s own Virtual Disk Image (VDI) format or in the third-party formats listed in the previous chapter • CD/DVD images in standard ISO format • floppy images in standard RAW format. As you can see in the screenshot above, for each image, the Virtual Media Manager shows you the full path of the image file and other information, such as the virtual machine the image is currently attached to, if any. The Virtual Media Manager allows you to • remove an image from the registry (and optionally delete the image file when doing so) • “release” an image, that is, detach it from a virtual machine if it is currently attached to one as a virtual hard disk. Starting with version 4.0, to create new disk images, please use the “Storage” page in a virtual machine’s settings dialog because disk images are now by default stored in each machine’s own folder. Hard disk image files can be copied onto other host systems and imported into virtual machines there, although certain guest systems (notably Windows 2000 and XP) will require that the new virtual machine be set up in a similar way to the old one. Note: Do not simply make copies of virtual disk images. If you import such a second copy into a virtual machine, VirtualBox will complain with an error, since VirtualBox assigns a unique identifier (UUID) to each disk image to make sure it is only used once. See chapter 5.6, Cloning disk images, page 79 for instructions on this matter. Also, if you want to copy a virtual machine to another system, VirtualBox has an import/export facility that might be better suited for your needs see chapter 1.12, Importing and exporting virtual machines, page 26. 75