HP Hitachi Dynamic Link Manager Software - Manual (Page 38)

2. HDLM Functions
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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 2-5: 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 2-6: 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 an example of an I/O
being issued for the same LU from multiple applications.