Installing GRUB on a VirtualBox guest - does it affect the host MBR?

Question

I am in the process of installing the latest debian stable on VirtualBox (3.1.4), and got to an installation step asking to installing GRUB to the MBR of the disk. I assume that since this is a "virtual" disk created by VirtualBox, that the MBR for it is isolated from the MBR of the primary disk on the host. Is this correct? I had previously been under the (possibly incorrect?) impression that there was 1 MBR per physical primary disk.

Answer 1

Quoted from http://www.virtualbox.org/manual/ch05.html#vdidetails

Disk image files reside on the host system and are seen by the guest systems as hard disks of a certain geometry. When a guest operating system reads from or writes to a hard disk, VirtualBox redirects the request to the image file.

So it does not affect the host MBR. Only the disk image file.