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

I have an older WD drive and there is a Mac version.  Here's the link that I went to.  Hope this helps.

Go here to find your drive:  http://support.wdc.com/product/download.asp?lang=en

My drive was under older drives:  http://support.wdc.com/product/download.asp?level1=1&lang=en

Then here (for me): http://support.wdc.com/product/download.asp?groupid=111&lang=en

If you aren't sure which drive if it's older... google the product number and you can see exactly which drive on amazon or somewhere.  That's what I did.

btw... it wasn't the Universal.  It was the following for my drive which was the latest software there.  I read the release notes and it was for data loss etc.  I didn't notice any date loss but thought the latest firmware/software would help.

• WD Drive Manager (Mac) 3.1.0

Try Jettison. This has solved all my external drive issues.

http://www.stclairsoft.com/Jettison/index.html

Not sure about these sleep related problems (my laptop never sleeps), but I have fixed the problem of the USB 3.0 drives disconnecting during file transfers.  Not an elegant solution, but a clean install of 10.9.4 with no Migration at all fixed the problem.

MIgration Assistant I tried for docs, music, and photos the first go-round, but it copied over all my app preferences and application support folders.  Not good, as getting rid of all that crud is one of the main reasons to _do_ a clean install in the first place.  The computer runs a little better overall, too, and I had the chance to upgrade a bunch of apps in the process.  And not install some others, like MS office.

I have also not reinstalled any background process or kernel extension things like Cubby or various Sony camera software.  I'll post here if I later on can pin the problem on any of those specific programs.  I remember someone blaming Google Drive for USB hard drive problems, and Sony installs launch agents and a USB probe extension that checks every time a USB device is plugged in.  All in the obnoxious pursuit of launching their software when you connect a camera.  At least you can tell iPhoto to not do that, but not Sony stuff.

I had one little glitch... it started ejecting my external HD again, so I un-ticked, 'Put hard disks to sleep when possible'.  It now works great.  Funny though, if my computer is idle, it still sleeps.  Could be because I told it to sleep in 15 minutes if idle.  Anyways, un-ticking the box as mentioned in previous posts worked in addition to ensuring that the latest WD software was installed. 

I solved a random disconnect problem with 2 firewire drives connected to my iMac running 10.9.4.  These are the steps I took - since I don't know which solved the problem I list them all - none are harmful if done correctly.

1. Turn off hard disk sleep in the Energy Saver panel
2. Repair disks and volumes using Disk Utility - First Aid
3. Eject and disconnect the external disks - power them down
4. Reset SMC http://support.apple.com/kb/HT3964
5. Reset PRAM http://support.apple.com/kb/HT1379
6. Use Maintenance http://www.titanium.free.fr and run all the default operations
7. Restart
8. Power up external disks and reconnect and check they mount ok
9. Repeat whatever was causing disconnection (e.g. backup to the disk) to test
10. If OK enable hard disk sleep in the Energy Saver panel if you wish.

This worked for me. Good luck.

This solved this problem for me.

I have been experiencing the same problem, with random disconnect of external hard drive.  I am running a 4TB WD, USB 3 on a iMac (Mid 2013) running OSX Mavericks 10.9.

I read on this thread that Google Drive might be the cause.  I was running google drive, but had only recently installed it.  I switched  it off, removed it from the applications folder, and since then I have had no further problems.

Thanks go to the chap that originally posted this.  I will report back if I have any further issues, but it was happening so frequently, and now it seems to have gone, I am pretty confident it was this.

Update:

The problem has come back!  What I noticed is that the drive dismounted any time my daughter logged in, or when I plugged in another USB device such as my iphone.

What I think I have resolved is that it was just a dodgy cable.  Reason - my daughter always wiggles the imac towards her or adjusts the screen, thus moves the cable, and when I plug in my iphone, I move the screen, on each and every occasion it drops the drive.  I changed the cable did the same test and it is now fine.

If this is as simple as this I feel like a bit of an idiot for assuming some issue with Mavericks etc.  Will post back in a week or so!

I am having same problems. Late i7, 27" Mac 3T Fusion Drive, 16gb RAM. It just auto un-mounts w/ same "ejection" error message.  I've seen some discussion of possible iTunes (corrupt file) related conflicts. (I rebuilt iTunes, reinstalled all my apps on my ios device. That seemed to help a small bit (perhaps bc iTunes is accessing 1000s of files at a time?? USB conflict? SATA card conflict?) 

Repairing and running DiskUtility/ permissions had virtually no long-term benefit -- even when done from a different boot drive.

Then I found this entry that Mavericks introduced a USB driver conflict that may affect HDs -- especially when copying/moving over 500 files (i.e. TimeMachine, running itunes or another HD cloning app. Mine wd crash when I was running SuperDuper-- which normally works great.) 

See this discussion: <http://www.enttec.com/support-center/kb/article/108-OS_X_Mavericks_(10.9)_-_IMPO RTANT> and

<http://www.dpreview.com/forums/thread/3605926> discussion of the problem.

I have also unmounted and unplugged my ext USB HD (used for backup-- but now have no way to clone my HDs.) I also disbaled the HD sleep function. That seemed to help so far. (Fingers crossed.)

Also, copying more than 500 files at a time seemed to create the crash (like if you were backing up your drives to an external USB connected drive.) Frustrating. Howver, this thread has been really helpful.

Please report back if you found a solution / fix. Thanks.

(Mac user since the original 512K, 1983.)

All of your (everyone on the thread) anecdotal issues points to a USB  (driver or hardware) conflict.  See my post about Enttec saying it is a USB driver conflict created by Mavericks. If you are using a thunderbolt connection, that would be one expensive work around.. but sheeesh.

This is frustrating beyond belief. I've tried a few things and nothing works. Thunderbolt does, of course, and I think my powered drive is ok, but my portables randomly disconnect. Seems to have become worse since some of the latest updates. I'm trying to clear some space off my tiny hdd and can't copy anything across to the portable! The irony is to reinstall I need to copy crap across. UGH.

Upgraded to Yosemite and my external drives Thunderbolt connected unmounting all the time!?!?!?!?

That's bad news.  Glad I haven't upgraded yet.  Things are still stable here after the Mavericks clean install.  Do you still have a backup of your pre-Yosemite boot drive?  Might not be too late to revert.

It appears the problem may have been due to using a Thunderbolt cable which was too long (6 feet).  I've got the drive on a very short cable, and it has not unmounted randomly yet.  Fingers crossed.

Update - late October 2014.

When I called Apple Support, they had me boot into SAFE MODE.

That helped for a bit, but a few hours the problem re-emerged, and the 2nd partition would auto eject unexpectedly.

Apple support recommended making a 2nd TEST admin user profile (to log into the computer with.).

No problems w/ the 2nd Admin log-in user name. Odd.

Use on the other user name seemed to also help/reduce the frequency with which the main user sign in name crashed w/ the old problem.

Will try re-installing the OS and fixing the user account.