'1GiB is the minimum allocation unit described by the OpenStack
Cinder API documentation.
* http://developer.openstack.org/api-ref-blockstorage-v2.html#createVolume # noqa
Some Cinder storage drivers may actually allocate more than
this, but as long as the requested size is a multiple of this
unit, the Cinder API will always report the size that was
requested.'

def allocation_unit(self):

    return int(GiB(1).to_Byte().value)
