HP XP P9500 Storage - Manual (Page 33)

paths and non-owner paths. If failures occur across some of the owner paths,
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 2-7 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 the physical paths (A)
and (B) cannot be used, the load is balanced between the physical paths (C)
and (D) (that is, between non-owner paths).
Figure 2-7 Overview of load balancing
When Using Other Than the Thunder 9500V Series and Hitachi AMS/WMS Series
All online paths are owner paths. Therefore, for the example in Figure 2-6
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.
Notes:
Load balancing is performed for the following storage systems:
¢
Lightning 9900V series
¢
Hitachi USP series
¢
Universal Storage Platform V/VM series
HDLM Functions
2-11
Hitachi Dynamic Link Manager User Guide for AIX ®