This option exists because it matches the traditional behavior of UNIX and some people might need it–don’t select this unless you know you need it for some reason. By default, Mac OS X doesn’t use a case-sensitive file system. OS X Extended (Case-sensitive, Journaled): On a case-sensitive file system, “file” is different from “File”.This file system is necessary if you plan on using the drive for Time Machine backups–otherwise, you’ll want to use exFAT for maximum compatibility. OS X Extended (Journaled): This is the default, but it’s only natively supported on Macs.RELATED: What's the Difference Between FAT32, exFAT, and NTFS? You’ll need to choose between several file systems: You’ll be asked to provide a name for the disk, which will appear and identify the disk when you connect it to a Mac, PC, or another device. Select the drive by clicking its name.Ĭlick the “Erase” button after selecting the entire drive to erase the entire drive and create a single partition on it. Your connected drives will appear under “External” in the Disk Utility’s sidebar. You can also open a Finder window, select “Applications” in the sidebar, and head to Utilities > Disk Utility.