The VirtualBox forums lists numerous reports of people not being able to get VirtualBox to work with raw disk partitions. Initially I bumped into the same problems, but got it working in the end.

The setup used in this article is an Ubuntu 12.04 host system with VirtualBox 4.1.18 installed. From disk /dev/sda the partitions 3 and 4 will be made available to a virtual machine. All virtual machines are run as user virtualbox. All console samples show clearly the user that runs the command.
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