Dell NetWorker 19.9 Administration Guide

AFTD load balancing

You can adjust the target and max sessions attributes per device to balance the data load for simultaneous sessions more evenly across available devices. These parameters specify the maximum number of save sessions to be established before the NetWorker server attempts to assign save sessions to another device.

For AFTDs, all volumes, depending on the selection criteria (pool settings), choose the AFTD with the least amount of data written to it, and join sessions based on the device's target and max sessions. If the number of sessions being written to the first device exceeds the target sessions setting, another AFTD is considered for new backup sessions and is selected from the remaining suitable AFTDs. The AFTD that is selected will be the AFTD with the least amount of NetWorker data written to it. The least amount of data written is calculated in bytes (not by percentage of disk space used) and only bytes that were written by NetWorker are counted.

To ensure that a new session always writes to the AFTD with the least amount of data written to it, you can set each AFTD device's max sessions attribute to 1. However, setting the max sessions attribute to 1 may not be practical. Alternatively, set the target sessions attribute to 1. In this way, load balancing will occur on a best efforts basis.