About the -modify option

Most configuration changes are made using the -modify options of the commands haclus, hagrp, hares, hasys, and hatype. Specifically, the -modify option of these commands changes the attribute values stored in the VCS configuration file. By default, all attributes are global, meaning that the value of the attribute is the same for all systems.

Note   VCS must be in read/write mode before you can change the configuration.
For instructions, see Setting the configuration to read/write.