Quickly Select the Startup Disk on the Mac OS X Desktop
Want to quickly find and select your boot disk amidst a variety of other internal and external drives? Just hit Command+Shift+↑ (Command + Shift + Up Arrow) to immediately choose the startup drive on the Mac OS X desktop from anywhere in the Finder.
This command is what the Go To Parent folder shortcut turns into when you hold down the Shift key, which is appropriate given the startup disk is the ultimate root directory to anything else on the boot volume.
Remember, if you’re looking to change the actual startup disk of the Mac, you can either do that on boot by holding down the OPTION key, or select a different startup volume from the System Preferences of OS X. Either works.