HP StorageWorks Auto Path VA Software - Manual (Page 23)

Auto Path VA Device Settings Window 23
Setting the Load Balancing Policy
The Auto Path VA Device Settings window lets you set the load balancing policy for a selected device.
All of the load balancing policies determine their actions based upon the current queue depths of all of
the paths available to the device. The only difference between policies is how they measure the queue
depth. All of the policies, except Round Robin, tend to shift the I/O load from heavily loaded paths or
resources to more lightly loaded ones. If the average number of requests outstanding to the device
tends to be small, then all of the policies behave like Round Robin.
You can select from these load balancing policies:
• No Load Balancing. No load balancing performed. All I/O is routed through the preferred path.
• Default Balance. Same as Shortest Queue Requests.
• Round Robin. The requests are cycled through each path sequentially without regard to queue
depth.
• Shortest Queue Requests. (Default) Measures the current queue depth by counting the number of
requests outstanding for each path.
• Shortest Queue Bytes. Measures the current queue depth by the sum of the I/O sizes of the requests
outstanding on that path.
• Shortest Queue Service Time. Measures the current queue depth by the sum of the length of time
each I/O request has been outstanding on that path.
To set the load balancing policy:
1. From the Devices window, select the server and then the array.
2. Select the device whose load balancing policy you want to set.
3. Click the Device Settings button.
This displays the Auto Path VA Device Settings window.
4. From the Load Balancing Policy drop-down menu, select the load balancing policy.
5. Click OK.
This applies the selected load balancing policy, and then displays the Devices window.