code: def snapshot_allocation(self):
  		
  		check_cmd = ['lvs', self.volume_path(), '-o', 'snap_percent', '--noheadings']
  		output = subprocess.check_output(check_cmd, timeout=self.__class__.__lvm_snapshot_check_cmd_timeout__)
  		output = output.decode().strip()
  		if len(output) == 0:
  			raise RuntimeError('Unable to check general logical volume')
  		return float(output.replace(',', '.', 1))
docs: Return allocated size (fraction of total snapshot volume space). If this is not a snapshot volume,
  		than RuntimeError exception is raised.
  
  		:return: float