After you have calculated the queue depth limit, you must apply it.
Each operating system has a way to limit the queue depth on a per virtual disk (VDisk) basis.
An alternative to setting a limit per VDisk is to set a limit on the host bus adapter (HBA). Thus, if the queue depth per path limit is 5, the server has access to 40 VDisks through two adapters (four paths). It might be appropriate to place a queue depth limit of (40×(4×5))/2 = 400 on each adapter. The queue depth limit of (40×(4×5))/2 = 400 on each adapter enables sharing the queue depth allocation between VDisks.