Functional Test 1. This provides information about a series of tests that indicate how well a physical drive works. These tests compare the way the physical drive currently operates when performing various tasks with the way it worked when it was new. A percent value is displayed that represents how the drive works currently when compared to how the drive worked when new. New drives operate at the 100 percent level. By default, if the current value is less than or equal to 80 percent, a problem may exist. If you suspect a problem, run diagnostics to verify that a problem exists. If the value cannot be determined, 4,294,967,295 is returned.