Hitachi Dynamic Link Manager, User Manual, Page: 43 / 746

2. HDLM Functions
19
2.7 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 to each path,
while others cannot. Therefore, even though load balancing function is used, I/O
operations might not be equally allocated to each path.
Figure 2-7: Flow of I/O Data When the Load Balancing Function Is Not Used shows
the flow of I/O data when the load balancing function is not used. Figure 2-8: Flow
of I/O Data When the Load Balancing Function Is Used shows the flow of I/O data
when the load balancing function is used. Both figures show examples of I/O
operations being issued for the same LU by multiple applications.