HP XP P9500 Storage - Manual (Page 38)

among the remaining usable owner paths. When all owner paths cannot be
used, load balancing is performed among the non-owner paths.
For the example in Figure 2-9 Overview of Load Balancing on page 2-16 ,
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 Lightning 9900 Series, Lightning 9900V Series, Hitachi USP,
Universal Storage Platform V/VM, Virtual Storage Platform, Hitachi AMS2000
Series, or Hitachi SMS
All online paths are owner paths. Thus, for the example in Figure 2-8 Flow of
I/O Data When the Load Balancing Function Is Used on page 2-15 , 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.
Load Balancing Algorithms
HDLM has the following six load balancing algorithms:
• The Round Robin algorithm
• The Extended Round Robin algorithm
2-16
HDLM Functions
Hitachi Dynamic Link Manager User Guide (for Linux(R))