If the storage system is supported by HDLM, usually all paths are owner paths. In this case, the load is balanced among all paths that access the same LU. If some of the paths become unusable due to, for example, a failure, the load will be balanced among the remaining usable paths.
For the example in Figure 2, the load is balanced among the four paths A, B, C, and D. If one of the paths were to become unusable, the load would be balanced among the three, remaining paths.