DiskMark is an application that lets you perform a speed test for your Mac OS X. Therefore, you can test the performance of your flash (pen/USB), solid state, and hard disk drives in just 60 seconds. The tool shows sequential read/write speeds, which is the performance you see when copying large files. In addition, it showcases random read/write speeds, which is the performance you experience when opening or using programs that read and write a lot of files from and to disk.