Yosemite ejects external drives

So would a external powered USB 3.0 Hub prevent this from happening?

With me same.
I use a Mac Book Pro and a Freecom Hard Drive Dock Duplicator and several WD Hard Drives. 1-3TB, Yellow and Green.

I did Spotlight off for those. This doesn’t help. The disks keep ejecting. When one ejects, it ejects consistent the 2nd.

After all this unintended ejecting they often don’t mount anymore at all

or 10.10.4 does them to read only. Disk Warrior does

repair this.

I suppose it has to do with some files: When I copy files, often it stops copying, tells me I can’t copy because

of a file. And ejects both external disks. When I copy without that file it works. This is a lot of work and slow.

When I try to copy an Aperture Library it says after 1,5 hours: I can’t copy this Library

and ejects both disks.

In common with everyone else posting here, recently some of my external disks began unmounting randomly from my newish Mac Pro. I have been searching for a solution and have tried most of the suggestions posted here, without success. On a related thread I stumbled upon advice to run the utility Kext, available as a free download. It appears to have cured the problem in one go.

However, to be clear, my problem was random un-mounting, unconnected with sleep.

I have been having this problem ever since I upgraded to Yosemite (approximately four months ago). And now I finally try to find a fix for it and see that it's been going on for nearly eight months! Is this pathetic or what?

Ever since Steve Jobs died, OS X and iOS have gotten worse and worse. Come on, Apple Engineers! You can do better than this!

I actually write software for a living, which makes this even more appalling to me. If we found a problem like this in our code, we'd be so embarrassed that we wouldn't sleep until we fixed it.

I was having trouble (as per everyone else) of my drives randomly ejecting. I have a mac mini (2012) and have 2 x WD Thunderbolt Duo Drives daisy chained via thunderbolt connecter.

I tried pretty much everything here software wise - verified permissions, repaired disks, etc to no avail. I monitored the console and pretty much disabled all of the programs which were popping up around the time of the disconnects including dropbox & logmein. I also bought 2 x new thunderbolt cables and downloaded and ran avast internet security for mac.

Voila! Drives are no longer disconnecting. I'm not sure which part of the multi pronged attack actually worked - I'm slowly re-enabling the programs to see if it was one of those that was causing the issue. I have already re-enabled sleeping & power sleep settings which hasn't hurt it & my next step is to re-enable spotlight. I actually suspect it was either the cables or a one of the issues that avast picked up.

Hey folks,

Thought I might really make your day...I'm on El Capitan Beta 5 and this problem is....NOT FIXED! Yeah, so you have that to look forward to.

I've connected my USB 3.0 external SSD with a USB power adapter that allows the drive to pull power from two USB ports on my brand new iMac 5k, and it resolved the issue where my drive was disconnecting every 10-15 minutes regardless of whether my computer went to sleep. Looking at 'System Information -> Hardware -> USB' it's showing that my USB3.0 drive enclosure is only linking up at USB2.0 and only being supplied with 500mA, and not 900mA.

Speed: Up to 480 Mb/sec

Manufacturer: ASMedia

Location ID: 0x14200000 / 1

Current Available (mA): 500

I did not have any issues with this external drive on my late 2012 iMac running the latest version of Yosemite. Unfortunately, that machine was stolen...

Anyone have ideas on how to make sure the external SSD links up at USB 3.0?

Going back to a direct connection to the iMac USB 3.0 port, it seems that it's the adapter cable, bridging power between two USB ports, that is causing the down-negotiation to USB 2.0. I'm going to try the Spotlight fix instead, since USB 2.0 is WAY too slow.

5K Imac with

3 external LaCie (from 1 to 2 Tb) connected with chained Firewire 800 + 3 TB Time Capsule connected through wifi.

My external drives worked fine for years with my previous 2009 iMac, worked fine for 7 months with my new iMac (Yosemite from the first day). My LaCie drives are ejected and reconnected (until now) since I got the latest OS X 10.10.5 (14F27) upgrade (three days ago). I got also two iMac system crashes (and reboot).

No problem with the time capsule.

Reading the posts I don't find any clue of a stable solution.

Energy saver tactics did not work.

Spotlight one : will see... But I'm a heavy user of spotlight.

Did someone got any help from Apple ?

This worked instantly for me... Apple please fix.. ASAP

My WD Mybook thunderbolt 4gb disconnectes soon as I booted-up my Imac (late2012) with 10.10.5.

My solution: deinstall WD Drive Utilities from programs!

Works like a charm now, you can (re)format with disk-utility, don't need the wd software.

Good Luck!

*** SOLVED FOR ME ***

Rig is Mac Mini 2011 / Thunderbolt Display / Westen Digital Thunderbolt Duo (daisy-chained to Display's additional TB port). Constantly ejecting Western Digital 8Tb Thunderbolt Duo also causing display instability after 10.10.5 update. I'd been documenting my pain over at Mac Mini Thunderbolt Display Instability 10.10.5 before discovering this discussion.

My steps to resolution have been as follows:

1. Perform SMC reset specific to your Mac.

2. Shutdown and disconnect Mac / Display from wall power.

3. Disconnect all peripheral connections except TB video cable (if Mac Mini).

4. Connect wall power. Boot Mac. Wait 10+ seconds before logging in.

*** Your system should now be free of display flicker issues caused by external HD instability ***

5. Shutdown cleanly and disconnect Mac / Display from wall power.

6. Disconnect video cable (if Mac Mini).

7. Connect TB drive cable to TB Display & Storage Unit. Attach Storage Unit power.

8. Connect wall power. Boot Mac. After chime, connect video cable (if Mac Mini).

9. Wait 10 seconds before logging in.

*** Your should now be able to see external HD attached (in my case) via Thunderbolt cable ***

10. Access System Preferences -> Energy Saver. Set both slider controls to ‘Never’.

11. Access System Preferences -> Spotlight -> Privacy. Deny access between Spotlight and External Storage.

12. Rescue External Storage content (if applicable).

13. Remove Western Digital Drive Management Software from Applications.

14. Format External Drive / create new RAID set using OSX Disk Utility.

15. Shutdown cleanly. Boot Mac.

16. Access System Preferences -> Energy Saver. Reset defaults.

17. Access System Preferences -> Spotlight -> Privacy. Deny access between Spotlight and new external HD Label created in Step 14.

*** Stability returned to rig ***

Thank you to all for support and encouragement. I hope these steps help someone out there with a similar setup.

This has happened multiple times since I have gone to Yosemite.

The basic items are in the sidebar Favorites such as Dropbox, AirDrop, Desktop, Applications, etc. All the items that I added manually are gone.

It's possible this is connected to another problem where the external drives randomly disconnect, as I believe these items are on the external drive.

Are you also having this happen?

Hi mrhoni ...

My personal experience has been a loss of visibility of anything associated with the external drive. The by-product of unexpected ejects will undoubtedly vary by configuration, but your experience does not sound unreasonable. Mine was loss of display stability and loss of external drive visibility even after re-boots.

Returning stability to your system whilst not deleting personal data/configuration is top priority. Good luck.

Thank you to those who got in touch about Step 16. Should read:

16. Access System Preferences -> Energy Saver. Reset defaults. Untick "Put Hard Drives to sleep when possible"

This resolves loss of USB/TB drives in Mac's which have sleep capability.