MAC PARTITION SOFTWARE BOOTABLE USB MAC
To start your Mac from the Recovery System, use these steps: You can also start your Mac from OS X Recovery or Internet Recovery if your Mac was manufactured after 2011.
Startup Manager automatically adds bootable volumes as you connect them. You can also attach FireWire or USB external hard drives that contain an operating system to add to the list of startup volumes. If you have an optical drive connected to your computer, you can insert an installation disc to see it in Startup Manager.