6 cloning disk images, 7 writing cds and dvds using the host drive, Cloning disk images – Sun Microsystems VIRTUALBOX VERSION 3.1.0_BETA2 User Manual

Page 85: Writing cds and dvds using the host drive, Writing cds and dvds using the, Host drive

5 Virtual storage

5.6 Cloning disk images

You can duplicate hard disk image files on the same host to quickly produce a second
virtual machine with the same operating system setup. However, you should only make
copies of virtual disk images using the utility supplied with VirtualBox; see chapter

8.17

VBoxManage clonehd

, page

127

. This is because VirtualBox assigns a unique

identity number (UUID) to each disk image, which is also stored inside the image, and
VirtualBox will refuse to work with two images that use the same number. If you do
accidentally try to reimport a disk image which you copied normally, you can make a
second copy using VirtualBox’s utility and import that instead.

Note that newer Linux distributions identify the boot hard disk from the ID of the

drive. The ID VirtualBox reports for a drive is determined from the UUID of the
virtual disk image. So if you clone a disk image and try to boot the copied image
the guest might not be able to determine its own boot disk as the UUID changed.
In this case you have to adapt the disk ID in your boot loader script (for example
/boot/grub/menu.lst

). The disk ID looks like this:

scsi-SATA_VBOX_HARDDISK_VB5cfdb1e2-c251e503

The ID for the copied image can be determined with

hdparm -i /dev/sda

5.7 Writing CDs and DVDs using the host drive

When you attach your host’s CD/DVD drive to a virtual machine (see chapter

3.6

Storage settings

, page

), this normally gives the machine read-only access to the

host drive. This prevents the guest from writing to the host drive. In particular, you
cannot burn CDs and DVDs from the guest this way.

As an experimental feature (which currently works for data only, audio is not sup-

ported), it is possible to give the guest access to the CD/DVD writing features of the
host drive (if available):

VBoxManage storageattach

--storagectl

--port

--device

[--type

--medium >]

[--passthrough ]

[--forceunmount]