USB, FireWire, Thunderbolt, and eSATA external devices feature “plug & play” connectivity, which means that your LaCie storage can be connected and disconnected while the computer is running. To prevent failures, however, it is important to follow these steps when disconnecting your device.
Drag the storage device icon to the Trash. (The icon pictured below is a generic USB device icon. Your LaCie storage may be represented by an icon that looks like the device itself.)
When the icon disappears from the desktop, the storage device can be disconnected.
From the System Tray (located in the lower right-hand side of your screen) click on the plug icon (note the white check mark inside a green circle).
A message will appear, detailing the devices that may be safely unmounted.
Select Eject for the device you wish to unmount. A message will appear notifying you that it is safe to remove it.