Disk Utility makes it easy to erase, format, partition, and create volumes, and to make RAID sets. Understanding the difference between erasing and formatting, and between partitions and volumes, will help you keep the processes straight.
Definitions
- Volume. A volume is a storage container that has been formatted with a file system your computer (in this case, a Mac) can recognize. Volumes are logical constructs; they’re not the same as partitions or physical hard drives. Volumes are most often made up of a single hard drive partition that contains a Mac file system. But it’s also possible for a volume to be made up of multiple partitions, something we won’t address here.
- Partition.The term ‘partition’ is both a verb and a noun. When you partition a hard drive, you physically create separate sections on the hard drive; each of these sections is called a partition. A partition defines a specific area of a hard drive.
- Erase. Erasing is the process of removing all data from a specific volume or hard drive. Data can be erased in multiple ways. The default method on the Mac deletes the data table entries for the location of the file, but does not actually remove the file itself from the hard drive or volume. The practical effect of this is that your Mac no longer sees the file, and the space it uses is now marked as available free space. You can also specify optional erase options that will completely remove the data.
- Format. Formatting a hard drive defines how the hard drive’s media will be laid out to store the computer data. Your Mac can use five different types of formats: Mac OS Extended (Journaled); Mac OS Extended; Mac OS Extended (Case-Sensitive, Journaled); Mac OS Extended (Case-Sensitive); and MS-DOS.
