Some suggestions:

  - allow multiple sort orders of LUNs, may be useful if there are a
    lot of LUNs [20130507]

  - add unit option for different size representations [proposed by
    Pascal Gregis 20121019]
    - done: -s: SI units for bytes; -ss: IEC 80000-3 prefixes for bytes
      (e.g. 3.56GiB); -sss: size as logical block count, exact in decimal
