Q: Disk not ejected properly

This problem is years old. It's been bugging me on Apple laptops since the days of the G4 ibook. Different computers, connection types, external hard drives - back comes the problem. Apple stuff is reliable, and so are the problems! I might try changing the computer name as suggested, but it seems an obscure solution - why should that make any difference when it seems to me to be an inherent fault?

Sorry Apple, but I think it requires a proper fix.

Like a few other people have mentioned, my "Disk not eject properly" (DNEP) issue seems to have been tied to a small power trip. I have a lot of power running in my office including a couple computers, a TV, and a mini fridge.  I finally noticed that I would see the DNEP message when the fridge would kick on.  I unplugged the fridge last week and haven't seen the DNEP message since.  Still it wasn't an issue back on Mountain Lion or earlier, but my setup hasn't always been the same.  So think about how much power you're sharing on the same breaker with your External Disks.

"So think about how much power you're sharing on the same breaker with your External Disks."

@astoutj, that's about the most plausible explanation I've seen in the years I've been following this thread. The randomness of the DNEJ messages and failure of any configuration changes of any kind throughout multiple OS iterations from Mavericks through the beta El Capitan, along with Apple's seeming inability to fix it, suggests that power variations to the various hard drives may well be the answer. Some drives seem more likely to give the DNEP message, particularly USB drives with external power supplies. I've always had a problem with those, and none with my Thunderbolt external HD, which has no external power supply. Also, I get random "battery running low" or some such messages from my USB connected UPS, even though there's nothing of the sort going on.

I can't imagine what the fix is, then, since the computer or OS seems to be responding to an intermittent issue with the drives themselves, if you are correct about this, which I suspect you are.

I'm not getting any more HDs that require external power, and I may try to sell my WD MyBook on Ebay. Readers of this thread can look for it there and bid it up. :-)

I have two drives one has an external power the other is USB and the imac on my power..yet I still get this on both drives and sometimes individually so it is not a plausible explanation for all cases

I've now tried a number of different external drives. The only one that has consistently worked without ever giving me DNE errors is the LaCie Little Big Disk. Unfortunately, it is very expensive and has a limited capacity and application (very fast disk for video editing/photography), so it won't help many on this thread. Strangely enough, I tried other LaCie drives (D2 and 2Big) but they triggered the DNE error.

I can't believe this hasn't been addressed, since Apple has moved in a direction of limiting internal storage with the Mac Pro and other devices, essentially necessitating an external drive if you work with many or large files.

Perhaps we should start a list of external drives that don't cause problems?

OK, I withdraw my statement about plausibility.

We can start with a g-Technology G Drive Mobile, 1 GB, which runs on Thunderbolt or USB 3.0. I've only used it with Thunderbolt, so I don't know what happens with USB (maybe I should try that just to see), but in 6 months or so it has /never/ given me a DNEP error.

Has anyone tried the CalDigit T3 thunderbolt 2 enclosure? I'm considering this myself, but don't want to go there if I'm just going to get DNE errors.

I got my first Mac this January.  I have two external hard-drives, one for backups and one for my family tree info & photos.  The backup one never ejects improperly, always stays connected but the second one, disconnects improperly consistently.  I replace an older HD, which had been attached to my laptop, thinking that its age was the reason for the disconnects.  Nope still disconnects.  The old one never disconnected from laptop.  So I don't think it is a model issue but an issue with Mac going to sleep.  I saw somewhere that one person wrote some scripts that basicly pinged the hd every so often.  But I really don't want to go this route.

I have read some but all of the comments here on the subject.  Tried removing everything from Spotlight like one user suggestions.  Nope still happening.  With so many people with this issue all with Apple products I think it is indeed an Apple issue.

I only have an all-in-one printer attached, besides this hd and the backup.  Oh & a desk light.

Apple please find a fix for this!!!!  Does Apple monitor this site???

Very frustrating! Just about makes me want my old laptop back......Sigh.....

Greetings fellow DNEP sufferers!

New poster to this forum here.  I have this issue on my 2013 Mac Mini with an external USB 3 Toshiba SATA drive (used for Time Machine), AND it happens on my 2013 MacBook Air with a PNY 128GB USB 3 flash drive and a Samsung 2.5" SSD in a USB 3 enclosure. Additionally, it has been known to happen while the computer is awake and being used.  It also does it when coming out of sleep mode.

Here is where it DOESN'T happen: on my 2010 Mac Pro tower.  That computer does not have USB 3 ports on the motherboard, but rather a third-party USB 3 PCIe card.  The external USB 3 WD SATA drive (used for Time Machine) connected to the third-party USB 3 card has NEVER had a DNEP issue. Not even once in several months of use.

All of these machines are running the latest version of Yosemite as of this posting (10.10.4).

Here is a question I have: does this problem occur when a USB 2 device is connected to a native USB 3 port?  I have an old external LaCie USB 2 SATA drive that I use for Time Machine on my MBA and have yet to see the DNEP.  In my world, the evidence seems to indicate that it is a USB 3 thing because I have not seen it with my USB 2 devices.

I perused all of the posts here and don't recall seeing this particular scenario being addressed; however, with so many pages of posts to sift through , it is entirely possible that I overlooked it.

Thanks for any input out there!

Forgive me, it has been a while since I reviewed this thread. Has it been established that for most (or all) people on this thread the DNE issue doesn't happen if the Mac is set to never sleep?

For the last year, I haven't had this problem at all. I have a retina iMac, with a LaCie Little Big Disk attached. It does not produce DNE errors, and I do have the computer set to sleep after 1 hour of not being used, and I always put it to sleep at the end of my work day.

However, while the LaCie Little Big Disk is blazingly fast, it's not very high capacity—only 1 TB. I do a lot of photography work, and I've nearly filled it up. One option is to get another Little Big Disk, daisy chain it to the first, and create a RAID-0. This would double the storage capacity and make it even faster than it already is (I regularly get 1,200 MB/s read/write speeds)... and it would hopefully allow me to continue without DNE errors, but it's a lot to pay for only a little more storage space, and it wouldn't be too long before I filled it up too.

I have to believe that this problem is restricted to a certain subset of users. There are hundreds of thousands of people out there with Macs that have external drives, and I doubt all of them have this issue or there would be even more activity here on the forums. The question is, why does it affect some users and not others? Why do some drives have the problem, but not others?

It remains a complete mystery. I've had this issue through multiple MacBooks and OS versions, starting clean, so it isn't just some computers or OS versions. It has happened on my LaCie USB 2.0 drive, long gone, and occurs on my WD MyBook USB 3.0 drive regardless of whether it's connected to the rMBP USB port or a 3.0 hub or a 2.0 hub. It has never happened to my G-drive 1 Terra Thunderbolt whether connected via TB or USB 3.0. That's the one that isn't externally powered, but I guess that theory has been discredited.

You would think that Apple could take some console logs from computers with DNE error messages and figure out what was going on.

Here is a question I have: does this problem occur when a USB 2 device is connected to a native USB 3 port?  I have an old external LaCie USB 2 SATA drive that I use for Time Machine on my MBA and have yet to see the DNEP.  In my world, the evidence seems to indicate that it is a USB 3 thing because I have not seen it with my USB 2 devices.

That's my experience too, yes. I have a four bay drive box here, with four individual controllers. They have available on each a USB3, FW800 and eSATA port. Each bay is occupied by a variety of hard drive units (Seagate, WD, and Samsung).

If I connect any of the bays to my iMac using USB3, either directly or through a powered hub, I get the DNEP any time my iMac sleeps, and reawakens. The drive icons are also disappeared from the desktop, indicating they really have been ejected. They reconnect again on waking up though.

I also found that it caused other issues too, probably more dependent on the individual drive unit being used. My main photo library is on one external drive, and Lightroom was unable to write anything to the drive while connected using USB3 (unable to move files or create new folders for example). Also, my Time Machine drive reported serious hard drive errors, indicating hardware failure.

Using USB2 showed no errors or problems at all, and everything works great. However, needing a little extra speed from my photos storage, I use a TB-FW800 adapter, and I daisychain the whole lot using FW800, and have absolutely no problems at all with that either.

My suspicion is that it is maybe down to how the Mac controllers work with USB3, I wonder if they inadvertently set the extra power feed to switch off during sleep mode, and this causes the drives (or the Mac system) to think they've been disconnected.

I perused all of the posts here and don't recall seeing this particular scenario being addressed; however, with so many pages of posts to sift through , it is entirely possible that I overlooked it.

I have mentioned this before, but, just to be helpful....

Cheers.

Hi guys,

I do not use USB3 on any of my devices (it's only available on 1 external LaCie), and still it happenend to me when I upgraded from 10.6 to 10.9 however, after following Apple's and this forum's advice (see previous post) and did a pram and power reset, my problems are gone. Maybe that's why Apple doesn't seem to bother?

mini (no USB3)

dvd fw 400

3 hd fw 800

Did removing third party apps and stopping it from shutting down on its own help?

Have been following this thread a long time, and although now on Yosemite a while, it doesn't seem to matter much.  Some external hard drives eject but on computer wake up remount; some eject occasionally (the same one might not do so for weeks and then start doing so); and I gather some eject quickly or are not even recognized.  There seems to be a myriad of partial fixes (like the ones you allude to) and attempted explanations of particularly scenarios (power fluctuations and load variances, USB 2 v. 3, etc.).  What has long been quite clear on this thread and others (some labelled for Yosemite) is that there are many moving parts and little published effort so far by Apple to address any of them. At a minimum, Apple ought to give a useful diagnostic chart on what is known, what is solved, and what is not.