HP XP Racks - Manual (Page 24)

I/O operations. This mode is recommended when the number of sequential I/O operations
is large.
•
Disable: I/O operation is performed with only one path that is normal and has the highest
priority. The same operation applies as that for Single path mode. When Disable is set for
Load Balance Mode, load distribution is not performed. This mode is not recommended.
CAUTION: Depending on the external storage type and system configuration, performance may
not be improved when Extended Round-robin is set. In that case, Normal Round-robin is
recommended.
External path configurations — direct and switch
This topic provides recommendations for setting up direct and switch external path configurations.
Direct connection
The following figure shows redundant paths in a direct connection configuration. External storage
system ports, "WWN A" and "WWN B", are connected to the local system ports, "CL1-A" and
"CL2-A" (which are specified as external ports). For greater redundancy, Path 2, the alternate
path, uses ports of a different cluster in both the local and external storage systems.
Switch connection
The following figure shows redundant paths with switches. Ports in the local system are connected
to ports in the external system through the switch. The paths use ports of different clusters for
increased redundancy.
24 Requirements and planning