Q: Anyone else having problems with external disks unmounting randomly/suddenly on Mavericks?

This is beyond annoying.  I have an external drive connected directly to USB port and another connected via USB 3.0 hub, and both eject themselves randomly and frequently.  Sometimes I also have old Firewire 800 Drives connected thru a Thunderbird to Firewire 800 adapter and those have never been ejected.  Not sure what that proves though.

Where is Steve Jobs?

I've been following this and other posts on the problem of drives disconnecting drives.

I have a 2TB USB3 WD myBook and a BlacX 5G plugged into the USB3 ports on a Belkin Thunderbolt Express Dock connected to my Mid 2011 27"iMac. I also have a Delkin Devices Card reader plugged directly into the computer's USB2 port.

The drives that I've had problems with have all been SSDs. Copying files from my CF and SD cards (8, 16 &32 GB) often results in the cards being unmounted by the system and showing the disconnect error. I have a 1TB & 3TB HDD that work perfectly on my BlacX but as soon as I plug in a 2TB Seagate SSHD which is a Solid State/traditional hybrid drive it also fails.

The failures do not seem to have any connectioin to which port they are plugged into as I've plugged the USB3 divices directly into the USB ports and I've plugged the SD cards directly into the built in card reader.

This does seem to be an OS issue as the devices have very little bearing on the outcome.

I also have a mid 2010 Mackbook Pro that I loaded with Mavericks using a clean install. I have had no problems with it, so I'm leaning towards the pain of a full clean reinstall on the iMac.

I've had this happening on several drives and enclosures for well over a year..........I thought it was me........the total randomness of this issue is enough to make me ask "Does this happen on windows?" fwiw I've been widowsless since 2013.

I read about SMC reset here.

http://forums.macrumors.com/showthread.php?t=1703575

Apple directions here,

http://support.apple.com/kb/ht3964

It has worked so far. I would like to find others that have had positive results.

Some background:

3 weeks after Maverick update the improper ejection issue started. I did an Internet Rocovery to a Mini sold with Mountain Lion. Still no good, same ejection issue. After the SMC reset I Carbon Copy Cloned 14GB from HDD 1 to an external Seagate Freeagent Desk for Mac, no trouble. When I plugged in a second drive to the mini it was not recognized, I unplugged and am now "drag and drop" downloading 116GB from finder window to external Seagate Backup Plus for Mac.

Update: the drag and drop worked without isue.

This is doing my head in. Why has this been going on for so long and Apple (as per usual) dont even acknowledge there is an issue.

I've had better luck since switching to a Powered USB Hub. I purchased the Amazon Basics model and have had no random ejects on the USB 3.0 drives since.  I have yet to have any ejects from the Thunderbolt to Firewire 800 drives.

I have the exact same issue and the handful of people (i.e. idiots) who think it's faulty hardware need to wake up and get a clue. My Mac Pro is brand new and my Thunderbolt Drobo S is BRAND new, just got it in December when I ordered my Mac Pro. I first used it on my old Mac Pro running 10.8 and NEVER had an issue. Ever. As soon as I got the new Mac Pro running 10.9, literally the first night, it will now constantly "improperly eject" the Drobo S whenever the computer falls asleep for extended periods of time. I say extended because I've left for an hour or two and not had it happen, but when it's overnight, 8+ hours, without fail it disconnects my drive for no reason whatsoever. It's annoying because I haven't seen anything about 10.9 that I think is an improvement from 10.8 whatsoever, except this horrible malfunction that annoys the **** out of me.

JonathanLB .. Did you happen read/see my earlier posts? In case it pertains to you..I have pretty much the same hardware as you and had the exact same problem with my Thunderbolt Drobo. This may or may not help ..but in my case I had trouble syncing my iPhone 5s with a cable that was aftermarket due to the chipset in the new Apple Cables. It made me wonder about the Thunderbolt Cable I was using which was also an aftermarket cable. I took a chance and bought an actual Apple Thunderbolt Cable and like magic the problem completely disapeared.It has been close to 2 months now without a single "disc not ejected properly" message from the Drobo. I work editing video and need 10.9 to run the latest version of FCPX and Compressor. I understand the frustration, but calling people idiots doesn't really endear them to want to help. Hopefully this will help in your case as well.

My problem is with USB 3 not Thunderbolt. hick9 that looks like a nice way for Apple to increase sales of overpriced cables.

I never mentioned USB 3. I was answering a specific post for someone who has the same issue I had with a Thunderbolt connected Drobo.

Has anyone test USB3.0 with latest update 10.9.2?

In my situation problems with Welland ME-541S dual 3,5" extrenal USB 3.0 enclosure everythink with unexpected unmounting had gone. Now sleep iMac27, switch off and on iMac27, daily working tasks, TimeMachine update works fine - since update 10.9.2.

10.9.2 does not make any difference.

When I hear that the problem is with cables or the devices, I go crazy. I have a BlacX5G (USB3) Docking Station. I have a number of drives from 750GB to 3TB that all run fine. When I put in a 2TB Hybrid where the data is cached onto an SSD drive before being loaded onto the drive, it disconnects.

When I am downloading images from my CF  & SD cards thru a Delkin Devices USB2 card reader, it disconnects part way through the downloads. When I use the built-in SD reader, it disconnects part way through downloading. The cards are Sandisk (Extreme or better) or Lexar Pro 16 or 32 GB.

These devices all work on my White macbook running Lion. (USB2 only)

I use a 27in Mid 2011 iMac with a Belkin Express Dock providing the USB3 ports. USB2 devices are plugged directly into the computer. Last week I did a clean install of Mavericks to make sure that I don't have any old drivers in place. Before I restored the Time Machine backup, I tested the devices, it made no difference. Changing the cables made no difference. Plugging the USB3 devices directly into the USB2 ports on the computer made no difference.

I read on another site that I should patch the AppleUSBXHCI.kext. This did not work for me. I just kept getting an error message after I made the patch.

Hello there,

I've been having the same issue about disks unmounting randomly since I switched to the new MacPro late 2013.

I didn't have this issue on the previous mid-2010 MacPro.

It happened on two Vantec 4-bay hard drive and one Icy Box 4 bay hard drive, all three connected via USB3 (not at the same time)

I change the USB3 cables and now one of the two Vantec seemed to work correctly though I haven't test it for long yet.

The Icy Box showed the same issue so I'm thinking it is not hard drive or box related but something about the Mac or OSX or cables.

I even bought the Thunderbolt Express Dock from Belkin and connect the hard drives on there just in case it has to do with USB3 connectors on the MacPro.

So for now, one Vantec will go back to test on a different MacPro. The Vantec that works fine will go through some more testing. The Icy Box have Firewire ports so I connect it to the MacPro with Firewire800 with a thunderbolt adapter.

I'm still suspecting an OSX issue after all my testing with hard drives, cables and connectors configurations.

I have an Icy Dock USB3 2-drive enclosure and I was having the problem where it ejected when the computer was asleep for a long time.  Since Mavericks 10.9.2 however it locks up the file system (computer seems to sort of work, but apps can't launch, spotlight doesn't work, etc...)   Problem is fixed by unceremoniously unplugging the Icy Dock and re-attaching it.  This lock up also only happens after the computer has been asleep.

I've tried it with a USB3 hub and directly attached to the computer--no difference.  I tried it with some older USB2 enclosures (same drives) and they don't seem to do it.  It seems like the problem follows the Icy Dock enclosure, but the fact that the behavior changed from 10.9.1 to 10.9.2 makes me suspect the problem might really be some issue with USB3 on Mavericks.