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The I/O operation is distributed based on the path priority attribute. Paths that have a higher path priority value receive a greater share of the I/O operations. 

Set the algorithm attribute to  round_robin  before you add the hdisk to any volume group. All outgoing traffic is then spread evenly across all of the ports: 

chdev -l <LUN>  -a algorithm=round_robin 

The shortest_queue algorithm is also available in AIX for FlashSystem. The algorithm is similar to the round_robin  algorithm. However, the shortest_queue  algorithm distributes I/O operations that are based on the number of pending I/O operations on each path. 

The path that features the fewest pending I/O operations is selected for the next operation. The path priority attribute is ignored when the algorithm is set to shortest_queue . Therefore, if one path is slow because of congestion in the SAN, the other less congested paths are used for more of the I/O operations. The shortest_queue or round_robin  enables the maximum use of the SAN resources. 

To list the attributes of the LUN, enter the following command: 

lsattr -El <LUN> 

The output of the chdev  and the lsattr  commands of the FlashSystem 900 that is used in Example 6-1 on page 158 is shown in Example 6-3. The number of spaces in the output is changed for clarity. 

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