Ejecting a drive/partition/disk image in the Finder vs with Disk Utility

[LeChuck]

I have run into an issue with ejecting a disk image in the Frinder: right-click disk image --> eject
While the disk image (it is password-protected) diappears from the desktop, double-clicking the disk image dmg file will open the password-encrypted file without asking for the password. In order to really eject the disk image, I have to use the Disk Utility.

My second issue relates to the first: I have recently set up an external backup drive. Once I have backed up, I want the external disk to spin down. Since the disk does not spin down after a period of inactivity, I tried ejecting the drive. The external drive kept merrily spinning, and I had to turn it off via the power button. Next, I used the Disk Utility to eject the external drive. The disk spun down. I was also able to remount the disk via the Disk Utility.

Is this behavior normal? Shouldn't ejecting a drive/partition/disk image via the Finder works just as it does via the Disk Utility?

 

[LeChuck]

It appears that "ejecting" and "unmounting" are not the same thing. A search confirms that.

 

[LeChuck]

If I "eject" a partition of the external drive using the Disk Utility, the drive will spin down. I have to choose "eject partition." I can also mount the external drive and its partitions through the DU. If I unmount the external Drive in the Finder by right-clicking and choosing "eject," the drive will not spin down.

That means, when I "eject" in the Finder, the drive is really only being unmounted, but it is not being ejected.

 

[Morhass]

To take advantage of the Mac's excellent power management, both the hard drive itself, and the enclosure that it's in have to support power management. You won't find this in older, low-cost USB external drives designed for versions of Windows that didn't support power management...

 

[Kaveman]

Are you sure it was the drive still spinning that you could hear and not the fans, the fans never spin down.

 

[Morhass]

True, ejecting from Finder is different to ejecting from DU. A Finder eject simply unmounts the partition(s), it doesn't let go of the physical volume, because that's still connected at a physical level... A Finder eject flushes buffers and breaks any data-level communication between the Mac and the partition(s), thus preparing it for physical disconnection. Basically, Finder uses human language, which is enough for many users, while Disk Utility uses more technical language, so distinguishes between unmounting - releasing the data connection, and ejecting, which releases the physical connection.
Kaveman's correct in that it's very rare to hear a modern hard drive spinning, although I have had a few that appear to make a clunking sound when they're preparing to spin up. Normally, all you hear is the fan.
This comes back to my earlier point - if the enclosure the drive is in supports power management, when the drive is not in use it will spin down, good enclosures will then stop the fan because the drive isn't generating heat.
Sounds like the enclosure and drive you're using aren't aware of being unmounted?

 

[LeChuck]

Are you sure it was the drive still spinning that you could hear and not the fans, the fans never spin down.

The drive in question is a Newer Technology mini-stack. I used a stethoscope. I think it's the hard drive that I hear.

 

[LeChuck]

True, ejecting from Finder is different to ejecting from DU. A Finder eject simply unmounts the partition(s), it doesn't let go of the physical volume, because that's still connected at a physical level... A Finder eject flushes buffers and breaks any data-level communication between the Mac and the partition(s), thus preparing it for physical disconnection. Basically, Finder uses human language, which is enough for many users, while Disk Utility uses more technical language, so distinguishes between unmounting - releasing the data connection, and ejecting, which releases the physical connection.
Kaveman's correct in that it's very rare to hear a modern hard drive spinning, although I have had a few that appear to make a clunking sound when they're preparing to spin up. Normally, all you hear is the fan.
This comes back to my earlier point - if the enclosure the drive is in supports power management, when the drive is not in use it will spin down, good enclosures will then stop the fan because the drive isn't generating heat.
Sounds like the enclosure and drive you're using aren't aware of being unmounted?

Yeah, it seems like the drive does not realize it has been unmounted. Anway, it's not an issue any longer, because I now know that ejecting with the DU will do the trick.

 

[Morhass]

Not quite sure what's wrong with ejecting from finder then switching off or disconnecting the drive?

 

[LeChuck]

Not quite sure what's wrong with ejecting from finder then switching off or disconnecting the drive?

Problem scenario 1:
I have an encrypted disk image (.dmg), which acts like an external drive. If I use the Finder to eject, anybody can open the ejected encrypted disk image by double-clicking the .dmg file without entering the password. If I eject the encrypted disk image with the DU, opening the .dmg requires the password.

Problem scenario 2:
I have an external hard drive, which I want to remain unmounted after ejecting. If I eject with the finder, the external drive will automatically mount because DriveGenius wants to verify the disk or check SMART or wants to verify preferences for the external drive. I don't want my external drive to spin up and down every hour.

Ejecting the encrypted disk image and the external drive with the DU solves the issue.