Which virtual machine can boot from USB drive?

"I've found the solution for virtual disks VMDK compatible machines.

The steps I've done are the following:

Install Virtual Box
Determine the Physical Disk number of the USB drive. To achieve this I run the following script generated by WMI Code Creator:

strComputer = "".""
Set objWMIService = GetObject(""winmgmts:\\"" & strComputer & ""\root\CIMV2"")
Set colItems = objWMIService.ExecQuery( _
""SELECT * FROM Win32_DiskDrive WHERE Name = '\\\\.\\PHYSICALDRIVE1'"",,48)
For Each objItem in colItems
Wscript.Echo ""-----------------------------------""
Wscript.Echo ""MediaType: "" & objItem.MediaType
Wscript.Echo ""Model: "" & objItem.Model
Wscript.Echo ""Name: "" & objItem.Name
Next

Execute this from the VirtualBox folder, changing XXX with the number given by the script:

VBoxManage internalcommands createrawvmdk -filename ""C:\USB.vmdk"" -rawdisk \\.\PhysicalDriveXXX -register

Just create a new VirtualBox machine with just the whole disk, and start it. I've tried with VMware just forcing to use the USB.vmdk and the virtual machine starts but while loading the Operating System, just shows an error about slow device."

Not sure if this is what you're looking for, but the VMWare ESXi hypervisor will actually boot straight off a USB drive. HP actually sells servers this way.