Q: External hdd won't eject properly since El Capitan

Running this command from Terminal allowed me to eject the disk consistently:

    sudo killall mds

I cannot guarantee that this workaround will not have side effects (there is no documentation for the mds command) and must recommend that you not do anything important with your Mac between running this command and your next restart.

Of course, this is a bug and affected users should report this at https://bugreport.apple.com

Running El Capitan, my LaCie icon shows up as orange but never turns green. I can eject it without problems, but I'm not sure if the problem is El Capitan or the LaCie. I've added it to the spotlight > privacy list, but no change. Blue light is on on the LaCie. Any thoughts?

I also have this problem after upgrading to El Capitan. Oddly, however, it is only a problem on the USB3 drive. I have all Western Digital drives and the Thunderbolt ones and Firewire ones (connected through the Thunderbolt) dismount but the USB3 drives won't. The problem only occurs when I put the Mac to sleep (as opposed to shutting it down). Adding it to the Privacy list in Spotlight does not help.

I experienced no problem with disc ejection under 10.11.1, however I installed 10.11.2 on December 17th, and this is my log to myself about what happened on completion of my first full backup to an external drive (a Samsung partitioned into 5 'cycles') after that installation...

A reboot (logging out and switching off), leaving the external drive connected, does not cause the drive to be re-mounted. 

Physically disconnecting and re-connecting the drive after a reboot causes the drive to be mounted as normal, whereupon it can be ejected by method (2) above.   Method (1) still has no effect.

Although the state of the contents of Cycle 5 remains unknown, I have no reason to think it has been corrupted.

I had no problem with El Capitan 10.11.1 but the very first time I tried to eject an external disc after installing 10.11.2 this occurred.

What diagnostics can be used under these circumstances to identify the process claiming to be still using the external disc?

Hi guys,

I believe I found a fix, will report back if it happens to pop back up. This computer is 3 days old and has nothing on it, found it funny it wouldn't eject USB sticks, Seagate 3TB drive and a few of my G-Raid drives.  Here's what I did

- unplugged everything form the back but the keyboard

- closed out everything

- relaunched finder

- opened up Disk Utility

- ran first aid my HD

- clicked restart computer

- held down option + command + P + R (for three chimes)

Computer started with zero issues, now able to eject anything. I've tried my USB sticks about 5 times each, HD about twice (really don't want to do this to a spinning HD, USB sticks I really haven't had any issues with).  Well I hope that helps

Chris

I just deduced that the reason my USB3 drive is not ejecting upon sleep is due to a combination of El Capitan and my USB2 hub–that the USB3 drive is running off. My Thunderbolt and Firewire drives run directly off the the Thunderbolt port on the computer, and both shutdown when I put the computer to sleep. Yosemite and Mavericks were both able to shut down the USB3 drive through the USB2 hub, with no warnings when I woke up the computer. Inexplicably, El Capitan, however, does not like this configuration. When I hook the USB3 drive directly up to the computer, it works as it should, shutting it down and restarting it without any fuss. I just ordered a USB3 hub the other day and I am hoping that El Capitan will be okay with it. Unfortunately, it will have to run this way due to the paucity of USB ports on the Mac and my plethora of USB devices. I wish USB hubs were more reliable or Thunderbolt drives were affordable.

My external Time Machine disk is Toshiba and I'm having the same problem too.  Apple should fix their ****.

This also happens to me and my wife with multiple external hard drives made by multiple manufacturers. My mother-in-law's iMac even has this issue.

Of course "reboot the machine" is not a solution; I want to back up every day for example and often there is a lot of work going on. I'd should not have to re-create my entire workspace in the morning just to eject the stupid time machine backup disk. I just force eject, and nothing ever goes wrong, but it's a bad issue that has been around for a long time. The fact that it remains is distressing, mostly because I thought Apple was better than this. I guess it is a low priority.

Sometimes maybe it helps to add it to privacy on Spotlight ... ? ... but even if it did that's a really lame work-around to be forced into. And actually that doesn't work for me. Now, when I can't eject it, I look in the Spotlight privacy list and the disk is not there. If I try to add it, I can't because of an "unknown error". But when I plug the disk back in after I force-eject it, there it is again on the privacy list.

Is it because this issue is "solved", that Apple can't see all the evidence? Then at best they are collecting data from the support website very poorly. I guess the only reasonable conclusion is that Apple doesn't care about this issue, and is even hoping it will somehow push me to pay for iCloud backups.

I too have this problem.

Poking around the web I found that this is a known issue with El Capitan. One workaround is to open Activity Monitor, force quit "mdworker" which is associated with Spotlight, then eject disks.

I haven't tried this yet. Thoughts?

Force quitting mdworker does work.  There's a little app called "What's keeping Me.app" that I found via Google you can run to see what is holding on to any particular drive.  It gives the process(es) and PID(s) of the offending application(s).  It's always mds and mdworker.

I called Apple Care and was told to open Finder, go down to Devices, click on Show (unless your devices are already listed), then click on the eject button next to your external hard drive.  This worked.

So I have been having the same troubles with ejecting my USB drives ever since the El Capitan update also.  I think you guys have found a work-around by going to the privacy settings and preventing spotlight from searching the drives.  This is a good one that I will try, but I found this error the hard way one day when months of research on an encrypted iron key thumb drive was at risk.  I took it to Best Buy and a guy pretty high up in the Geek Squad plugged it into his windows computer.  The Geek Squad at Best Buy runs a proprietary software created in-house that apparently removes all permissions/restriction/limitations on files (for example I had one instance where a file kept asking me for an administrator password that I somehow must have linked to the thumb drive saving stuff from a computer at the hospital).  When he checked the drive there were hidden files that I didn't even know about (.DS_Store, .Spotlight-V100, .TemporaryItems, .fseventsd) apparently these are files that the mac puts on the computer so that it becomes accessible to Spotlight.  So we both found the problem just from different ends of the problem.  My issues still are multiple and if you guys have an answer that would be awesome.

1. If I use my thumb drive at home on a macbook pro running OS X El Capitan but also have to use at work which are mostly windows based PC's that all require me to log-in my own "windows" and I'm not the administrator level, then what is the best way to transfer files to/from the thumb drive and the PC's and my mac without running into these issues?

2. There seems to be a difference when I drag/drop a file vs when I copy a file then paste a file to the thumb drive.  The latter seems to be the preferred method, because the drag/drop method seems to "connect" the file.  This is just from my experience and I'm not a computer whiz, just from hours and hours of dealing with this since the El capitan update.

3. If I proceed with the work-around by preventing spotlight from searching the drive, do I have to delete these hidden files before this work-around will work?  Which of these hidden files can I just delete without corrupting the drive?  This is such crap that these added hidden files are reeking such havoc on my thumb drive and my life right now.  I can't use dropbox/google drive at my work because they are blocked by the hospital software, or I would just do this.  I have to use a hospital approved iron key that encrypted or I can't use a thumb drive to save my work.  Ive searched for getting rid of the above files and keep getting crazy stuff like renaming folders/files (http://apple.stackexchange.com/questions/6707/how-to-stop-os-x-from-writing-spot light-and-trash-files-to-memory-cards-an…) and it starts to get over my head pretty quickly and get into stuff that in my hands could compromise the whole drive.  It's gotten to the point where its difficult to even use a thumb drive on my mac and I find myself emailing files to myself and have to keep remembering to download them and add them to the thumb drive while I'm at work.

Any help would be amazing (Kicking myself for downgrading to El Capitan)

Thanks for this tip.  This problem has been bugging me even with Yosemite.