"Disk Not Ejected Properly" error after EL Capitan goes to sleep and wakes up again.

I had this problem recently running the latest El Capitan 10.11.x. This bug has been around since 2009 based upon reports I read on the forums. However, it no longer occurs (fingers crossed) since I updated yesterday to Sierra 10.12.2. Occurred every time previously on wake from sleep with latest updates for El Capitan with two external Seagates connected to a late 2012 iMac. It's been reported on various Mac Hardware with many different external drives on the forums as early as 2009. This bug may finally have been fixed.

IM running 10.12.2 on a 2015 retina iMac. Seagate Time Machine drive - no problem.

WD My Book Studio dismounts itself while the Mac sleeps overnight, corrupts the volume partition and despite successful repair via Disk Utility, cannot be remounted. its there, but it's not there! Not even in Terminal. Only solution seems to be erase and reformat every morning!!! And that's with a replacement drive under warranty 4 days ago.

i Believe, but I can't be sure that this started with 10.12.2. It worked seamlessly for a year.

ive ejected the drive this evening. We'll see what the morning brings.

not reassuring as a backup is it?

I have a brand new 21" iMac running El Capitan. When the computer sleeps, my Lacie 1 TB external via USB disconnects, as well.

I tried the SMC reset also, which didn't work.

There are 14 pages of people with this problem here today. It is a real issue and needs to be addressed by Apple.

Update: Jan 18, 2017... I never solved this problem and had to turn off the sleep function on the computer. It is an ongoing problem...

On another note. Lacie external drives are susceptible to bad power supplies. I found this out recently when trying to use a drive that had previously been giving me problems. It was making a clicking sound and the repair shop said the drive was bad. When I got home I tried a power supply from another one of my drives that was exactly the same rating and the drive worked perfectly. So, power supplies (the full cord from drive to wall basically) will go bad on these drives and then they won't work. Find a new power supply chord if you have problems with your Lacie externals...

The Apple loosing connection with Lacie drives when going to sleep is an Apple problem on their side. The code that takes inventory of all plugged in peripherals is bad. It is easy to remember plugged in items in a variable form and check for them again when the computer wakes from sleep... Apple just doesn't want to fix this.

I haven't been able to reproduce the bug even once since I updated to Sierra; it was happening continually in El Capitan. I have had WD drives fail within two years, so I never buy them anymore. As stated in my earlier post, I have two Seagates and no problems at all now. So the bug I was seeing is fixed.

You should try updating to Sierra with the latest software update. I haven't reproduced it again since I updated, and it was driving me nuts before running El Capitan and reproducing every time the system went to sleep. Apple clearly fixed something with that release.

Several things done: changed firmware on 2009 Mac Pro from 4,1 to 5,1 ( MacPro2009-2010FirmwareTool.zip ), installed Sierra, updated to 10.12.2, read the latest in this thread, turned on my USB 3.0 drive dock, opened Keep Drive Spinning app to allow the drives it had been keeping awake to sleep -- and the USB dock drives work as they should, with no sudden ejections.

Nota bene: the firmware change is a hack and is not supported by Apple. That said, it appears to work well for a large number of users who have early 2009 Mac Pros that were eliminated from the Sierra upgrade path.

Update

after a number of days ejected and mounted when needed, the results are patchy.

sometimes fine, sometimes unreadable but dismountable but on one occasion I had to wipe and start again.

So, replacement drive being returned.

hope for better next time.

Why, yes. http://tinyurl.com/zmtx5tc

I first installed Sierra on my Mac Pro this way, before switching to the firmware hack that is not available for a 2008 machine. There is an issue with continuing updates -- when I tried, an update came at dial-up speed. Things may be better, now. I'd try it out on a spare boot drive before committing, but it should work.

I had one incident of it again, on Feb. 5 upon wake from sleep and I hadn't seen it for weeks once I updated to Sierra and 10.12.2. and yes, I'm running 10.12.3. Not sure when this OS update occurred, but the problem had gone away completely with 10.12.2. iMac late 2012, with two Seagate external drives connected. Thankfully I have only seen it once.

This error appears to be with us several years already without Apple caring/being-able-to fix it.

I've tried many of the "solutions" reported (some against my basic understanding of OS - like disabling the "turn off of drives when not in use for a while) to no avail I recently found another one - an application called "Mountain" (in the Appstore) that mounts/unmounts drives and shares - and apparently keeps them mounted (I have them there for 48h - never happened before).

I will report to the community if the drives are still mounted and no error notified in 2 weeks (when I return from a vacation). I left on a single 8TB with two partitions connected directly to an iMAC.

I have had this same problem with my 27" iMac and 4GB WD My Book Studio since Yosemite. I've since upgraded to El Capitan hoping that this would fix the problem, but to no avail. I have tried lots of suggestions found elsewhere (disabling Spotlight on the device, resetting the PRAM, etc, etc) but nothing seems to work.

It also does not need to be going to sleep for this to be a problem - it will drop the device in the middle of working at the computer. The worst is when I am working on my Photos library which is housed on the device and the device drops. In such an occasion the Photos library gets corrupted and needs to be repaired... I am at my wits end and I really hope someone can offer a suggestion to fix this problem.

Same here. Never had the issue with Yosemite, but not suffering disconnects while using. Drives still showing in finder so they're still mounted.

Same here...didn't happen prior to the El Capitan upgrade. It only seems to happen when the Mac goes to sleep, and it seems to happen multiple times during sleep, as if the computer was waking for some task, then going back to sleep. When I wake it, there are multiple "not ejected properly" notifications neatly lined up on the screen. Nothing seems to be wrong with the disk...it's always available and working fine.

I have the same problem since El Capitan. Happens constantly when I'm working in Lightroom or Photoshop. HDDs are plugged directly into the Macbook's USB ports.

If I wind up with a pile of corrupted images I'll be well p*ssed off.

How can Apple allow this to continue for so long, and be unable to correct it over so many versions?

I have the same issue on my new MacBook Pro, never had the problem before El Capitan.

However, some people report that the disk reconnects after sleep. Mine does not. This means my backups after being ejected improperly, do not reconnect after sleep. So I'm not getting backups. This is a major problem. I'm hoping my backups are not getting corrupted. A bad thing to have to hope for the best.

I use three different external portable drives to backup. Same problem on all of them - Seagate and WD.

A bug that disables backups and perhaps corrupts backups IS A PROBLEM!!