OS X Mountain Lion Bible

Working with Disks and Other Storage Media

The terms volume, drive, and disk are often used interchangeably to describe storage media, but you should know the differences:

• Volumes can be any storage container that a Mac sees as a distinct container (meaning an icon displayed in Finder windows' Sidebar), including disks, partitions, and network file shares. In this book, I use volume to mean network file shares, which can be of other computers, disks, or folders on other computers or drives—basically, any storage resource available via the network.

• Drives are the physical mechanisms that contain one or more disks.

• Disks are the media—composed of one or more circular recording platters—that actually store data. They can be magnetic, such as hard disks and floppy disks, or optical, such as CDs and DVDs.

• Partitions are sections of a disk that are presented to OS X as if they were separate disks. (You create such partitions when formatting the disk using OS X's Disk Utility, as explained later in this chapter.)

Note

There's also a form of storage called solid-state media, such as the MacBook Air's SSD drives, those ubiquitous flash-memory-based “thumb” drives, and digital cameras' flash-memory-based SD cards. Solid-state media don't actually have disks (instead, they're basically memory cards, like the RAM in a Mac, that retain their contents even when there's no power), but because the term “disk” has stuck as a generic term of storage, they are often called solid-state disks ...