'Prepare an instance for live migration
:param context: security context
:param instance: nova.objects.instance.Instance object
:param block_device_info: instance block device information
:param network_info: instance network information
:param disk_info: instance disk information
:param migrate_data: a LiveMigrateData object'

def pre_live_migration(self, context, instance, block_device_info, network_info, disk_info, migrate_data):

    raise NotImplementedError()
