Load Balancing really does not have much to do about this, unless you set a Load Balance MAX=1, to force each object to a different tape drive
What you should be looking at is Concurrency, which is the number of data streams that can be flowing to any one device. The default is 4. In your scenario, "file system (C/ drive, D drive/ )" would be 2 data streams, which would not even meet the minimum concurrency of 1 drive, so, all the other drives would be sitting there waiting
Most modern tape drives (LTO4 and above) can easily handle a concurrency of 10 or more
What Load Balancing will give you is that DP will use any of the drives selected... but, only that one drive
When doing a Restore, DP will always use the device used for backup, by default. If you want to select a different drive, there is a tab in the Restore context named 'Change device'
