Carbon Copy Cloner effectively and easily clones a drive in its entirety, so you can put a new drive in and change out hard drives. This is extremely important for many reasons. First off, if your drive is showing SMART errors, and you know the drive might fail soon (which you can find out by using Onyx), you will want to get a new drive in there ASAP. Also, in our case, the client wanted to go from a 240 GB drive to 1 TB in order to increase his disk space. I would also recommend using this if you want to use a solid state drive, as that is becoming the go-to for fast, reliable hard drives.