HP XP7 Storage - Manual (Page 29)

load balancing will be performed among the remaining, usable owner paths.
It is only when absolutely no owner paths are available, that load balancing is
then performed among the non-owner paths.
For the example in Figure 2-9 Overview of Load Balancing on page 2-11 ,
suppose that in the owner controller of LU0 is CHA0. When the LU is
accessed, the load is balanced between the two paths A and B, which are
both owner paths. When one of the paths (A) cannot be used, then the LU is
accessed from the only other owner path (B). When both of the owner paths
(A and B) cannot be used, the load is then balanced between two other, non-
owner paths (C and D).
Figure 2-9 Overview of Load Balancing
When Using the Universal Storage Platform V/VM Series, Virtual Storage
Platform Series, VSP G1000 Series, Hitachi AMS2000 Series, Hitachi SMS Series,
HUS100 Series, or HUS VM
All online paths are owner paths. Therefore, for the example in Figure 2-8
Flow of I/O Data When the Load Balancing Function Is Used on page 2-10 ,
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.
Note:
When using Hitachi AMS2000 series, Hitachi SMS series, or HUS100 series
storage, if the dynamic I/O path control function is disabled, all paths are
owner paths.
HDLM Functions
2-11
Hitachi Dynamic Link Manager (for VMware®) User Guide