HP XP P9500 Storage - Manual (Page 31)

Figure 2-6 Driver Levels of the HDLM and MPIO Drivers
Distributing a Load Using Load Balancing
When the system contains multiple paths to a single LU, HDLM can distribute
the load across the paths by using multiple paths to transfer the I/O data.
This function is called load balancing, and it prevents a single, heavily loaded
path from affecting the performance of the entire system.
Note that some I/O operations managed by HDLM can be distributed across
all, available paths, and some cannot. Therefore, even when the load
balancing function is used, a particular I/O operation might not necessarily
allocate data to every available path. RAID Manager issuing IOCTL to a
command device is an example of an I/O operation that cannot allocate data
to every path.
Note:
Do not use the load balancing function that is accessible from the
Microsoft iSCSI Software Initiator user interface.
In a cluster environment, the load balancing function is available for the
Thunder 9500V series, Lightning 9900 series, Lightning 9900V series, Hitachi
AMS2000/AMS/WMS/SMS series, Hitachi USP series, Universal Storage
HDLM Functions
2-11
Hitachi Dynamic Link Manager User Guide for Windows ®