The MPIO Policy defines how the host distributes IOs across the available paths to the storage. The Round Robin (RR) policy distributes IOs evenly across all Active/Optimized paths. A newer MPIO policy, shortest_queue, is similar to round robin in that IOs are distributed across all available Active/Optimized paths, however it provides some additional benefits. The shortest_queue policy will bias IOs towards paths that are servicing IO quicker (paths with shorter queues). In the event that one path becomes intermittently disruptive or is experiencing higher latency, shortest_queue will prevent the utilization of that path reducing the effect of the problem path.
The shortest_queue option was added in AIX version 6.1, Technology Level 9, and in AIX version 7.1, Technology Level 3.
Our ODM defaults to "round-robin", so if you would like to take advantage of the shortest-queue setting, you will need to run the following command:
chdev -l hdiskX -a algorithm=shortest_queue
Keep in mind that you will need to manually make this change anytime you overwrite the ODM (i.e. upgrading the ODM).
You can put the ODM fileset into your lpp_source, generate a new spot (which gets tftp’d to the client as part of the bootp process by NIM network install) and it will resolve the multiple disks issue at NIM network install.