Yosemite ejects external drives

As you will see in later posts this problem is still present in El Captain. I am using 10.11.3 and tested this a few days back. When I put my iMac to Sleep the drive ejected. As people have noted it certainly have a wide range of situations that it occurs. Sure wish Apple would fix this.

Same issue here. It's to the point that my external drive (connected to Mac Mini via Thunderbolt) ejects itself after about 20 seconds. On the phone right now with Apple Support and they're gathering data from my computer and sending it to the tech folks. I even showed the Apple Support rep this forum to show them it's not a unique issue or pertains to just a certain type of external drive. I'll update when I hear back, she said maybe 4 days or so.

OK, I found a fix that works for me and I bet it works for others. Here's the quick answer...

If your external drive is plugged into a surge protector with battery back up... plug the external drive into an outlet that doesn't have the battery back-up.That's it. That's the fix.

Here's a little more detail in case my answer wasn't clear...

I have an APC surge protector with battery back-up. It has a total of 8 outlets. 4 of the outlets are for surge protection only (and don't provide battery back-up). The other 4, in addition to surge protection, also provide battery back-up if the power goes out.

I just spent 15 minutes turning my computer on and off and switching plugging in my external drive from surge protection only to surge protection + battery back-up. Every time it was in a battery backed-up outlet, it would eject itself when I turned on the computer. But, every single times I plugged it into surge protection only (with no back-up) no problem!

I have no clue why that is. Maybe an electrician or battery expert can chime in.

Earlier in this thread, someone had mentioned he thought it had something to do with the electrical current. That's what led me to trying the different outlets. So whoever first brought that thought up...THANKS!

No that's not the issue for me, my drive was connected to a surge protector but not one with battery backup and I have tried it on a dedicated power socket as well and it still gets ejected. This is so frustrating, you spend money on getting the best drive money can buy and it keeps getting ejected.

The only things that seem to make some difference have been:

1) Turning off drive sleep/hibernation - this has definitely made a difference but not completely

2) Having less external drives running at once also seems to be a factor - if I manually eject my backup drive and just have the samples drive running I don't get as many ejects, but it's hard to see why this is a factor as the backup drive is USB (and is a powered drive on a powered hub) and the samples drive that is ejecting is Thunderbolt.

The more I learn, the less I know.

This is an amazingly difficult issue. Given all the different scenarios, I wish there was a way to track how often this happens, or to discern how aware Apple is of the situation. I'm also starting to wonder if this also happens on Windows machines. It really does seem as though there is some kind of basic electrical / voltage issue that affects external drives with touchy power supplies.

Anyway, just to add to the confusion...

Responses from both AppleCare and OWC (vendors of my external HDDs) have been prompt and helpful. AppleCare spent a good hour on the phone with me, and though the cause was not pinpointed, I did learn some valuable details on how things work in general. OWC granted me a replacement 4-bay enclosure, as my warranty was still in effect. Though I wasn't enthused go evaluate a third enclosure, this one set up perfectly; I put it through its paces (tasks performed directly on the HDD, and also a series of backups), and it works fine, as though nothing was ever wrong.

All of which makes the cause of this eject issue less clear than ever.

In my case, I still suspect my iOS update a couple weeks ago had something to do with it. I can only remember that the next time an iOS update is available, and research it before updating. (Or declining; it's just an iPod touch, un-sync'd to the iMac.)

I guess the other thing I can do is report the issue to Apple (again) and hope there is enough evidence piled up that will prompt Apple to acknowledge what is an obvious problem, even if it happens to a minority of users.

Otherwise, it seems my best bet is to simply get lucky with this week's gear.

Since manually ejecting all other external drives except my Thunderbolt drive I haven't had it ejected so clearly there is a link. Even though the other drives are USB 2 drives could it be because they all share a common PCI buss? It can't be power as they are all powered drives. I still have a networked drive connected and that isn't causing any problems but that one won't be using the PCI buss at all.

Please add me to this list of frustrated mac owners.

Lucie thunderbolt drive constantly disconnects from my top of the range retina iMac...

come on apple..... this isn't a new problem, get a fix already!

;-(

I have had this problem since upgrading from a MacBook Air to a MacBook Pro.

The following instructions worked 😁 and are posted here: Disk not ejected properly

Copy if the link isn't working

Instructions

1. Pull out your ethernet cable and disable WiFi and any other network connectivity you have.

2. Open Finder, go to your computer and then select you Macintosh HD (or whatever you have renamed it).

3. Go to Macintosh HD - Library - Preferences

4. Scroll all the way to the bottom of the list and you ewill see a folder called SystemConfiguration

5. Pull this folder onto the desktop.

6. Go to System Preferences - Sharing and change the name of your computer, even just a litlle bit.

7. Reboot

8. Re-enable Wifi and Ethernet

9. If you have installed Jettison, remove it and remove it from your start up items.

You shoudl be good to go.

Instructions

1. Pull out your ethernet cable and disable WiFi and any other network connectivity you have.

2. Open Finder, go to your computer and then select you Macintosh HD (or whatever you have renamed it).

3. Go to Macintosh HD - Library - Preferences

4. Scroll all the way to the bottom of the list and you ewill see a folder called SystemConfiguration

5. Pull this folder onto the desktop.

6. Go to System Preferences - Sharing and change the name of your computer, even just a litlle bit.

7. Reboot

8. Re-enable Wifi and Ethernet

9. If you have installed Jettison, remove it and remove it from your start up items.

It worked! No more disconnects all day!

Thanks for sharing. cypacs.

I'll keep it handy for the next incident. If there is one. Since replacing my external 4-bay enclosure (covered by warranty) I've had no issues. Though that suggests a problem with the enclosure, I'm still not convinced it's not an Apple hardware/firmware thing.

That procedure seems pretty arcane; I looked up the original post by Robster50; it goes back a couple years or so.

I found this interesting for my situation:

"So I called Apple support and pushed it very hard until I had a Teir 2 person on the line and she was incredibly helpful, supportive and instisted she woudl ge the problem fixed and she delivered. She pinned the problem down to the migration from the older machine/prefs corruption."

In my case, this was happening on two iMacs, but each was a clean install with no migration.

Either way, it's good to gather more information. Even more encouraging that someone got to Apple Support so directly. I also got fairly far in via AppleCare, but we couldn't exactly resolve anything. Other than suggesting that my upgrade of iOS via iTunes (which immediately preceded this round of trouble) MIGHT have launched a routine USB drive update. Which MIGHT have triggered problems.

Hopefully I've seen the last of this, and will consider forgoing anymore iOS updates. (It's just an iPod touch, which is offline 99% of the time.)

Sad to report that after 24 hours of uninterrupted operation the problem has returned 😟

I will continue to monitor this thread to see if a final solution emerges.

Rebooting fixes the problem until sleep mode is evoked, and the problem then returns.

And conversely, I've been routinely putting my iMac to Sleep, as I always do when I step out, and the problem still hasn't returned.

There is no figuring this out!

I still wonder if it's some kind of electrical / voltage issue in the various ports.

Also still wonder if the various Windows machines suffer from this.

Problem solved!

I have an external USB expansion device purchased at an Apple Store featuring five ports.

The disc was one of the devices plugged into this device.

The disc is now plugged directly into one of the two USB ports available on the MacBook Pro.

No further events for 24 hours or when the sleep mode is activated.

Conclusions: There is some hardware difference between my older MacBook Air and the brand new MacBook Pro.

Well, I'm glad your problem is solved.

Or - - - I hope your problem is solved.

I never use a hub. Critical stuff is always connected directly to my iMac. And mine is a new-ish 2013 model.

It did exhibit the problem in that configuration, but hasn't since swapping out the external enclosure.

Still no cause or cure as far as I can tell.

But maybe we'll both get lucky going forward.

2 weeks after Yosemite upgrade. For me the issue started yesterday when I unplugged the external HD power cord from power bar and plugged them back but in different spot. Also had an issue 3 days ago where I lost wireless connection between my iMac and my HP printer. Couldn’t even add a printer to the list. Tried everything that I know of to get the wireless connection back but failed so I had to use a USB cord for direct connection and printing.

I removed the printer USB connection from the iMac thinking that was the only real thing I changed and placed the external HD power cord back in it’s previous location on the power bar. So far no messages regarding improper external HD ejection.