Test the performance of your hard disk
To test the speed of your hard disk:
Open the Disk Utility application from the .
Choose the hard disk from the Storage Devices list. Information about the disk and its status will appear under Drive.
Click Start Read-Only Benchmark to test how fast data can be read from the disk or Start Read/Write Benchmark to test how fast data can be read from and written to the disk. The latter option will take longer to complete.
When the test is finished, the results will appear on the graph. The green points and connecting lines indicate the samples taken; these correspond to the right axis, showing access time, plotted against the bottom axis, representing percentage time elapsed during the benchmark. The blue line represents read rates, while the red line represents write rates; these are shown as access data rates on the left axis, plotted against percentage of the disk traveled, from the outside to the spindle, along the bottom axis.
Below the graph, values are displayed for minimum, maximum and average read and write rates, average access time and time elapsed since the last benchmark test.