Hi, The docs are not HP designed, they are other vendor with another backup software.
In this case, the NDMP remote is not suported for this storage in found this information in the manual of X9720:
The NDMP backup feature supports the following:
NDMP protocol versions 3 and 4 Two-way NDMP operations
Three-way NDMP operations between two X9300/X9320/X9720 systems
Thanks a lot.. Diogo