Q: Mountain Lion improperly ejects external disks

My HD (see a couple of posts earlier) has been working without any ejection message since July 23 now, i.e. for more than a month. Fingers crossed.

What did you do that is different?

Just read through all posted issues and it's obvious that this is completely a Apple Mountain Lion problem and not 3rd party.

I have been using Snow Leopard for 2 and a half years and other mac systems before that and have never seen a USB drive eject in my life.

2 days ago I formatted my drive and did a clean install of the latest Mountain Lion 10.8.4

And guess what? Now ALL my USB devices have suddenly started auto ejecting.

This is nothing to do with 3rd party firmware.. or power devices or hubs or anything. Even my simple  2, 4 and 8 gig little USB sticks are getting booted out now at regular 15 minute cycles.

I have set the 'Energy saver' to not let the computer go to sleep ever and will see what that does.

I agree - it sure seems like a Mtn Lion issue. I recently bought 2 new Western Digital backup drives. Both of them are being routinely ejected during the night. Interestingly, the ejection does not have any effect on anything. The drives are remounted every time automatically. It is just an irritating error message that pops up nearly every morning.

As I suspected.. the Energy saver' to not let the computer go to sleep option was the problem. Not one of my USB sticks or USB external drives has ejected all day.. 12 hours now.

Job done.

Don't hold your breath about the energy saver being the source of this issue. A number of people on this blog have tried that without permanent success.

I hear you AM until a permanenet solution is found it will have to do for now for me. I'll keep an eye on this thread as Apple don't seem to be sharing any of their wisdom.

I had the same issue with my new MBA and a new external LaCie Rugged USB 3.0 Thunderbolt drive, though only when I connected via the USB cable. I went through the Cardano procedure (LaCie firmware installed, Energy Saver reset, com.apple.TimeMachine.plist trashed) and additionnally had Jettison installed (suggested by Partyguy81). So far it works though somebody ought to check out each one of the four possible solutions, time permitting.

After several days of no spontaneous ejections, I believe this was the solution that fixed my issue. Thanks for the detailed post!

I'd be interested to hear how from others who have tried the solution that Cardano reported on July 23 and found it successful in resolving the improper ejections.

CARDANO's solution (7/23/13):

1. I updated the WD firmware (I am not sure that was necessary, but it could not harm either) - see your manufacturer's instructions for that
2. I reset the energy options on the iMac (go to Preferences/Energy Saver and untick the first box (Put hard disks to sleep when possible) as well as the third box (Allow power button to put the computer to sleep). I am not sure the second untick is necessary, but I found than in another post, and I did not like that feature anyway
3. I deleted the preferences file for TM (Click on Macintosh HD so the Finder opens, go to Library/Preferences/ and delete the file called "com.apple.TimeMachine.plist". The computer will create a new one.)

I did everything desribed above apart from the firmware update (there is no firmware update for little USB mem sticks) and I did not delete the preference file either as I do not use Time Macine at all.

However reseting the energy options seemed to fix it for me.

Well, I tried Cardano's recommendation and it has had zero impact. I'm still getting about one improper ejection warning message every day. Fortunately, it does not seem to have any negative effect on my hard drives. What a pain!

Yes it makes no sense at all.

I have even reset my Preferences/Energy Saver settings back to default and nothing is being ejected now.

***!

This has been happening to me since updating to Mountain Lion 10.8.5. I have a USB 3.0 external hard drive that I use for Time Machine. Every now and then I get a message randomly appearing telling me I didn't eject the drive properly. It's pretty stupid really. Was working fine until updating to 10.8.5. Gonna try the repair permissions thing and report back.

This has been happening to many others going back a lot farther than OS 10.8.5... It is a mystery that no one, including Apple, has solved with a universal method that applies to everyone. Some report actual damage to the external drives. Others, like me, simply report feeling  frustrated by  getting these routine error messages, but do not report any damage done.