This directive enables a bug workaround for Isilon 9.1.0.0 systems where the NDMP namelists tape offset (also known as fhinfo) is sanity checked resulting in valid value -1 being no more accepted. The Isilon system sends the following error message: 'Invalid nlist.tape_offset -1 at index 1 - tape offset not aligned at 512B boundary'. The workaround sends 0 instead of -1 which is accepted by the Isilon system and enables normal operation again.
