During an SSD over-provisioning test, SSD Profiling Tool first fills the SSDs with random data. It then tests the random write performance of the SSDs over several test phases, each using a different amount of over-provisioning. For example, if a test is created with a test range of 0-20% and a test interval of 5%, SSD Profiling Tool will test SSD write performance in 5 phases, with over-provisioning set to 0%, 5%, 10%, 15%, and 20%. If the random write performance of the disk is very low during any phase, SSD Profiling Tool will end the phase early and move to the next one.