How to Mount an External Hard Drive on Mac OS

By Marshal M. Rosenthal

A external hard drive attached to a Mac cannot be recognized by the OS X operating system until it has been formatted and mounted on the desktop. You can format and mount an external hard drive on your Mac using the included Disk Utility program. The procedure is straightforward and does not require any previous experience in working with external hard drives. You will be able to use the external hard drive to do any and all of the things that the hard drive installed inside of the Mac can do.

Step 1

Plug the cable attached to the external hard drive into the USB or Firewire port on the Mac, depending upon the kind of external hard drive being used.

Step 2

Launch the “Disk Utility” program by double-clicking its icon inside of the “Utilities” folder, which is inside of the “Applications” folder.

Step 3

WaIt for the icon of the external hard drive to appear in the left column of the program. Click once on the icon of the external hard drive with the mouse.

Step 4

Select the “Erase” tab at the top of the program's window. Select “Mac OS Extended” from the “Format” drop-down menu.

Step 5

Name the external hard drive in the “Name” column just below “Format.”

Step 6

Click the “Erase” button at the lower-right corner of the program’s window. Click the “Erase” button in the pop-up window that appears.

Step 7

Wait as a progress bar indicates the external hard drive is being formatted. Click the “Done” button on the pop-up window that appears when the formatting is done.

Step 8

Wait as the external hard drive is mounted and an icon of it appears on the desktop. Quit the “Disk Utility” program.

Tips & Warnings

  • Give the external hard drive a unique name so it won't be confused with any of the internal hard drives on the Mac.