I currently have two physical Ubuntu Server 10.10 servers at home: one serves as our firewall/router/DHCP/VPN server and the other performs double-duty as a file server and a VirtualBox host for an Ubuntu Desktop 10.10 machine which I use from remote connections (via NoMachine) for many thin-client purposes which are irrelevant to my question.

What I'd like to accomplish is to consolidate the two physical machines into one which is a dedicated VirtualBox host (most likely running Ubuntu Server 10.10). Note that I'd like to stick with VirtualBox (if possible) because I'm most comfortable with it and use it on a daily basis at both home and work. Specifically, I plan to have one VM set up as file server, another as the firewall/router/DHCP/VPN (or possibly split those a bit) and a third, which is the only current VM (already VirtualBox), which is the thin-client host.

My question comes down to performance and/or recommendations about the file server VM. The file server hosts about 6 terabytes of data across 4 drives. What I'd like to do is use raw disk access from the VM directly to the existing disks. However, I'm curious what performance advantage/disadvantage that would have as compared to using shared folders from the VM host and basically just have the whole drive served as a shared folder to the VM which would then serve it to the other machines on the network. I don't know if virtual disks would even work in this scenario and I certainly wouldn't want a drive to be filled with just a single file which is 1.5 TB (disk image).

To add understanding of context, but not to get additional advice, I want to virtualize these machines because I intend to regularly use the snapshot capabilities of VirtualBox for the system disks (which will be virtual drives) of the VMs and I have some physical space/power needs to address (as I mentioned, this is at home).