Q: Randomly ejecting USB hard disks

Western Digital My Passport Ultra 500GB purchased in April 2014.

WD Elements 500GB

Jan 15, 2014

Corrupted while performing Time Machine backup running on OS X 10.9.3. Now in the process of RMA.

Same for me on 2 devices:

1) Macbook Pro later 2008 with a Western Digital wd5000bpvt

2) Mac Pro early 2008 with a WD MyBook 1 TB USB 2.0

Before upgrading to Mavericks, not a single issue.

I'm having the same issue with a brand new MacPro 2013.  I didn't have any issues till I added a thunderbolt enclosure, after which my USB3 disk started randomly ejecting.  I suspect this is a software issue, but who can say.  Very annoying, Mavericks has so many issues! 

Same problem with Western Digital 1TB USB 3.0 multiple partitions

I suspect hardware problem, because after reconnecting the cable, I can hear what sounds like "efforts" to position the head. It will take multiple reconnecting attempts before I succeed attaching it again.

I just bought a brand new iMac 27", delivered just this June 2014. I used time machine to bring over my old computer's data just fine, but since then I can't seem to get my hard drive to stay on for more than 5 minutes before the computer has the audacity to tell me I should eject the drive first before shutting it off. When I click ok on the message, the drive powers down, and then immediately powers back up and reappears on the desktop. I fear this will wreck havoc on the drive and have been afraid to attempt using it again since. I have pretty important files on there, and can't even keep it up long enough to get them off.

LaCie 301425U 1.5TB d2 Quadra Hard Disk eSATA/FireWire800/FireWire400/USB 2.0 External Hard Drive Bought 2010.

I have been using the usb cord to connect it to my imac, as it is an older drive. This drive worked beautifully on my ancient white mac book from 2009, and other than the slothlike speed of my old mac book, it has worked SOLID for me. I sank several thousand dollars into this new desktop, and I find it hard to believe it is giving me more problems than my laptop-shaped hard drive (my macbook's screen and keyboard eventually failed, but I was still using it just fine with a monitor).

Oh, I have to mention that I am using a usb cord to connect the harddrive - I never used usb on my laptop with these drives before, because my laptop had a firewire port. I haven't tried hooking up the laptop with a usb cord to see if that's an issue, but somehow I doubt it is. Sounds more like a problem with the Mavericks OS.

I have an iMac 27", running 10.9.4 and two Oyen Digital U32 Shadow USB 3.0 drives, both connected directly to the USB ports on the Mac (not through a hub). One of the U32 drives remains connected with no problems. The other has been ejected randomly twice in the last 24 hours. As far as I can tell nothing has changed on the Mac in terms of hardware or software in this time. Hoping this doesn't become a chronic problem, but after reading this thread, I'm not optimistic...

There is a known issue where USB 3.0 interferes with wireless devices such as a mouse or a keyboard. (See e.g. http://www.intel.com/content/www/us/en/io/universal-serial-bus/usb3-frequency-in terference-paper.html) and I figured this may also be the other way round. So I moved te drive, that was disconnecting regularly, further away from my wireless keyboard and mouse (I had it positioned under my iMac, 15cm away from my keyboard). Maybe a bit early to say, but over the last 24 hours I had no disconnects. I will keep you posted.

Wow, this is so out there. I only have one wireless device, the trackpad, and i really wonder about it because only when i'm actively using my computer did my drives keep ejecting randomly. I did a time machine backup with no issues, perhaps it took long enough for the trackpad to fall asleep ? I really hope that this is the cause of the issue, though it is an almost unbelievable theory. But hey, i'll take any explanation at this point.. Do let us know if your drives ejects randomly ever again (not suggesting you purposefully move your wireless devices closer to see what happens, but I'm not going to lie, this would be really fabulous if it was the answer !)

After 48 hrs still no disconnects. Looking promising.

Disappointment: this morning unfortunately another disconnect

This went a totally different direction for me, I guess. Around the same time I had problems with disconnecting USB drives, I occasionally had a disconnecting Thunderbolt drive as well. Until recently the Thunderbolt ports gave up all together. After a discussion with the Apple Genius bar it appeared to be a hardware problem and I had my mother board replaced. Since then both my Thunderbolt and USB problems seem to be over. It's been almost a week now and no disconnects so far.

So, disconnecting USB drives might turn out to be a hardware problem.

So you brought in your imac, or had it shipped out? Did the apple genius say this was a common problem, hence the motherboard replacement? I wonder if most imac users just dont bother with external harddrives so apple can just let this fly under the radar.. And was your imac under warranty so it was replaced no charge? Thing is I dont use thunderbolt drives so I wonder if they might try to blame my harddrives, though they worked perfectly on my old macbook!

For inexplicable reasons this problem seems to have cleared up for me in the past week and a half as well. Hoping I didn't just jinx it.