I think we are having a communication problem.
Here is what I meant:
If your
computer is shut down or restarted from the Apple Menu (Apple Menu -> Shut Down... or Apple Menu -> Restart...), then you need not eject your external drives manually by dragging them to the trash. They will unmount automatically and safely as your computer shuts down or restarts. There is no danger of corruption or damage to an
external drive by properly shutting down or restarting the
computer without first ejecting the drives.
What I mean by "properly" is using the Apple Menu (or keyboard shortcuts) to shut down or restart the computer. You should
never receive a message that you improperly disconnected a drive if you perform a "proper" shutdown or restart. If you do receive an error message to that effect if you properly shut down or restart, then there is something wrong with something, somewhere, concerning your computer and/or drives connected to the computer.
An example of an
improper shutdown would be yanking the power cord out from the back of the computer, or holding down the power button on the computer until the computer shuts off. In this scenario, yes, data corruption can happen. You will receive an error message that states that the drive was improperly disconnected from the system.
An example of an
improper unmount procedure would be to yank the USB or FireWire cord out of the computer without first dragging the external drive's icon to the trash and waiting for it to disappear from the desktop and/or Finder window sidebar. The act of the drive disappearing from the list of drives after dragging it to the trash tells the user that it is safe to power off and/or disconnect the drive from the computer. Some people don't realize there's a required pause between dragging the icon to the trash and powering off the drive -- you can't do them in quick succession. The proper procedure is:
1) Drag external disk icon to trash
2) Wait for disk icon to disappear from the Desktop and/or Finder sidebar
3) Power off or disconnect the external disk
This procedure only needs to be done if you intend on disconnecting the drive from the computer while still using the computer or keeping the computer powered on.
Help me out here; What is an enclosure? Thanks.
An enclosure is the actual plastic or metal box that, well, is basically your external drive. It typically has a USB, Firewire or eSATA port, a port to connect a power cable, and sometimes an on/off switch. It houses an ATA or SATA base disk drive, pretty much identical to the hard drive that is inside your computer. It "encloses" the actual drive.