Linux, Ramdisk.
pvcreate /dev/ram0 Physical volume "/dev/ram0" successfully created. # vgextend ol /dev/ram0 Volume group "ol" successfully extended # vgscan --cache Reading volume groups from cache. Found volume group "ol" using metadata type lvm2 # lvconvert -y -m 1 ol/root /dev/ram0 Logical volume ol/root