Resize VDI
VBoxManage modifyhd debian-squeeze.vdi --resize 5000
Clone disks
VBoxManage clonehd baseOS.vdi baseOS-work.vdi
Clone disk, unsupported method
VBoxManage internalcommands sethduuid copied_disk.vdi
Control CPU for running instance
VBoxManage controlvm deb32 cpuexecutioncap 50