Q: Disk not ejected properly

Just got off the phone with LaCie. Maybe there is some light at the end tunnel after all. Accordingly to LaCie its probably a case of bad firmware. They will replace my drive. Once its back i will let you guys know if it indeed fixed the problem. Well cleaned the drive.... lets wait and see.

I too have this problem.  Preferences did not have that file and although I did all the other parts of the post, it didn't work.  Looks like it is just one of many El Capitan problems.

Ok this is what has happened to my case :

I have a Mac Pro 2008 and just installed an OWC PCIe SSD few days ago. I tried to backup my iTunes library (2.4 TB) to an external 3TB hard drive (via PCIe's eSATA dock). I was expecting that it would be completed at least for 12 hours (the machine was in default of Energy Saver), however, in the morning I realzed my Mac Pro has been restarted and a sign that the disk has been improperly ejected.

I thought may be the cable was not plugged tight enough therefore I recloned the hard drive again, however, after few minutes, the clone action was stopped and a sign of Disk not ejected properly appeared again.

I have repeated the above, and same thing happened and eventually my hard drive got corrupted and needed to be replaced.

I am not sure whether it is hardware or software issue, therefore, I decided to replace the whole OS X from my previous backup. After the restore completed, everything seems ok (at least till now)

Therefore, I suspect that one of the system file may got corrupted, so restoring the OS X from previous one should solve the problem, meaning it is not an OS X nor a hardware problem in my case

My Mac Pro has three OS X on different bays i.e. 10.11, 10.10 and 10.10 (PCIe), it only happened with the 10.10 (PCIe)

Thank you, this worked for me on El Capitan.

Thought I'd share a bit of good news, at least for me...

Current setup:

- iMac (27-inch, Late 2013)

- Processor 3.4GHz Intel Core i5

- Memory 32 GB 1600 MHZ DDR3

- Graphics NVIDIA GeForce GTX 775M 2048 MB

- External drive: Vantec HX4R eSATA/USB 3.0 RAID enclosure containing 4 x Western Digital WD30EFRX RED NAS-rated 3TB disks

For over a year now I've been battling with the good old "Disk Not Ejected Properly" dialog on my external drive. For me it wasn't happening when the computer was sleeping but instead when I was actively using it. I could either saturate the external drive with write traffic (e.g.: copying lots of multi-gigabyte files) OR I could saturate the CPU with user tasks, but if I tried to do both at the same time I'd be guaranteed to get the DNEP dialog within a few minutes.

Having read through this thread a couple of times I'd tried various solutions offered:

- I'd been to Energy Saver preferences and unticked "Put hard disks to sleep when possible".

- I'd confirmed that the setting had taken effect in Terminal using: pmset -g | grep disksleep

- I'd been to Spotlight preferences > Privacy and excluded the HX4R from Spotlight indexing (as annoying as that was, being unable to search the drive).

- I'd even borrowed another HX4R enclosure and a set of Seagate disks to confirm that it wasn't my hardware.

I was convinced that it was a timing or race condition bug somewhere in the JHFS+ driver or the USB3 driver. Until last week.

Last I moved my entire computer setup to a sit stand desk and then I started getting the DNEP dialog when barely anything was happening to the drive. Even just logging in to the desktop. Disk Utility would also pop the dialog just a few seconds into Verify Disk or Repair Disk activities.

It turned out to be, for me at least, the USB 3.0 Type B cable connecting the iMac directly to the HX4R enclosure. It must have always had a fracture and then when it got moved last week became a full-blown break. And I must have used my cable when trying the other enclosure. Since getting a new cable I haven't had the DNEP dialog pop once. *Fingers crossed* *Knock on wood*

I'm sure this won't apply to everybody, but hopefully it will prompt someone to try different cables and maybe fix their problems. Good luck!

I finally have found a  solution to my DNEP problem but it may not work (or be useful) for everybody.

I use the 'Mountain' application (see website http://appgineers.de/mountain/ ) to control external disks. In the latest version (1.6.2) there is an option to prevent disks from mounting upon connection (but you can still mount them manually).

With this option activated,  I haven't seen any DNEP for the problematic external disk so far, also upon wake from sleep.

This solution is only practical if you do not use the external disk that often (luckily my TimeMachine disk does not give DNEP errors). Every time you need the problematic disk you would have to mount it manually, but with Mountain it's only one click away.

This also worked for me as I had migrated to a new MacBook.  Huzzah!

Would you please let me know how can you fix the problem?

As the post to long,not easy to find out the solution.

Thanks a lot.

Add me to the list of people with the "Did Not Eject Properly" problem.

All Hardware is BRAND NEW out of the box 4 weeks ago:

iMac 27" Retina 5k (Late 2015)

El Capitan 10.11.4

External drives:

1. LaCie 2Big 6T Thunderbolt2 RAID 0

(External Power, Thunderbolt directly into the iMac)

2. GTechnology G-Drive 6T USB 3.0

3. GTechnology G-Drive 4T USB 3.0

(Both on external power, both connected to a USB 3.0 hub, connected to the iMac)

From day one, the LaCie 6T RAID has ejected itself ALMOST every time I wake the iMac up from sleep. Never when it was in use. But when I put the iMac to sleep, and wake it up the next morning, the LaCie 6T RAID is gone from the desktop and I get the error message. If I unplug the Thunderbolt cable from the back of the iMac and plug it back in, the LaCie shows up on the desktop and everything is fine.

The GTechnology G-Drives connected with USB 3.0 have never ejected themselves... Always work perfectly.

I tried getting rid of the thunderbolt cable from the LaCie and connecting it with the optional USB 3.0 cable and continued to receive the error message and ejections.

HHave you tried to reinstall your OS?

No, I have not tried that. It is a brand new iMac from Apple. This problem happened the first day I got it and plugged in my brand new LaCie RAID drive. I've read almost this entire thread and had not seen reinstalling the OS as a solution to this problem. Do you really think that might work?

I Am not too sure. But it worked in my case. I think I got some system corrupted

If reinstalled the OS does not help, then it could be hardware issue, and likely your Lacie.

I bought 4 Seagate hard drives recently, and two got corrupted and needed to be replaced.

I think a bad hard drive may cause this issue

I don't know whether this will be any help at all, but by fluke I found something today which may explain this message. I have never had it with my new macbook pro, (although I did get it regularly with my old macbook air) Anyway, I was having problems with pages taking ages to load, and someone suggested adding a Google DNS server to my server list - I think one was 8.8.8.8. and there was another one as well. It didn't sort out the problem I was having, but when I connected my hard drive to do my daily backup, sure enough, there was the message, which kept on popping up, so I couldn't back up. I removed the added DNS servers, and have had no problem since. Backup was fine.

Maybe it was coincidence, but I thought I'd put in my two halfpence worth - it just may help someone 

Ok. It's been about a week now and I feel that a combination of a couple of the "fixes" recommended here have worked for me. Originally I tried the solution provided by @Robster50 (Robin) and it seemed to work for a few days, but the 'Disk not ejected properly' issue returned. In the end, doing all these things appears to have worked for me:

1. The original solution provided here by Robin
2. In Settings > Energy Saver unchecking 'Put hard disks to sleep when possible'
3. In Settings > Energy Saver checking 'Prevent computer from sleeping automatically when the display is off'
4. In Settings > Spotlight > Privacy added all the external drives to NOT be indexed by Spotlight

I'm not 100% sure if the last item is required or not and I may experiment with that and report back here. I did have one time in a week where my Time Machine drive did report the 'Disk not ejected properly' error but that is FAR better than before when I used to get these errors on multiple drives multiple times a day.