Q: External hard drive ejects on sleep

I guess your only option is to change your system preferences under energy saver to only put the display to sleep and never let the computer or hard disks go to sleep. That way your external drive will never be ejected unless you have a power failure.

Same here, we are running 2 computers that I am backing up via ethernet while we (and the computers :-) are sleeping.  And to reply to Zepple about changing the energy saver preferences, that is an option although for me at least, a waste of energy.  I will look into the App that Zepple suggested although I don't know if it will solve my particular problem with sparse image bundles (see my post at the beginning of this thread).

The Jettison app will not work in your situation since as soon as your computer goes to sleep the external drives will be ejected. They will remount only when your computer is woken up.

Whoops!  Bummer, but you just save me $1.99 :-)   Until (or if) Apple ever gets around to fixing this I guess I'll just have to live with remounting the sparse image drive each time. Thanks for the tip though.

Thinking about it a bit more Jettison may work. When you are backing up the internsl hard drive must be awake even if the display is off. That would also mean that the external drive should mount. Worth $2.00 to find out.

I have turned off both computer and disk sleeping and my drive still disconnects randomly, and often.  I can't get it to stay mounted for more than a few hours at a time.  I do have display sleeping on.  I don't see how that should affect anything.

I am also using Fast User Switching, which I suspect might be part of the issue here.

This is my issue as well. My new USB 3 Seagate for Mac drive will just randomly eject. The only way to re-mount is unplug and re-plug.

Went ahead and bought Jettison, I just hope this solves the issue.

In the past, I've had hardrives corrupt when ejected improperly, and my Thunderbolt Big Disk is full of important stuff.

Thought I was out of the woods with Mavericks but spoke to soon.....though, ML is running okay since supplemental update.

Yep, same here.  Computer sleep is turned off (for power adapter, and I'm plugged in when this happens), and Put hard disks to sleep is also turned off.  Display sleep is set to 10 min.  I've had this problem ongoing for months.  Over the past year, I bought new drives and a new USB hub, and I just upgraded to Mavericks.  No change - still having the problem with both external drives, one of which is connected directly and one of which is connected through the hub. 

In fact, after upgrading to Mavericks, now my external display ALSO becomes inactive upon waking.  I have to unplug the display cable from the laptop and plug it back in for it to work. 

This is ABSOLUTELY RIDICULOUS.  And the fact that this drive problem has been occurring for this long with this many people is outrageous, especially since Apple no longer ships laptops with mechanical drives (which have much more storage), pretty much forcing you to use an external drive. 

I've been a Mac/Apple fan for over about 25 years (even worked there for a year), and never have I seen so many problems than in the past couple years (not just talking about these issues - their entire cloud system is a mess among other things).

The same here too,even with the 10.9.1 update! It doesn't happen everytime I put the computer to sleep but enough times to make it annoying.

This happens with a clean install of Mavericks on a brand new SSD. So what now Apple?

This was posted some time back and it worked for me without causing any problems:

  macbirdy
Re: External hard drive ejects on sleep
Jun 7, 2013 4:20 AM (in response to iamapple)
Hello everbody
First of all: sorry for my english, I'm Swiss... I discovered this discussion after having bought a new iMac 27" last saturday. From the beginning, my two external hard drives (LaCie 2Big Quadra and LaCie D2 Quadra), both connected via USB3, have been ejected as soon as my Mac went to sleep. In most of the cases, additionally my Mac re-started after a kernel panic. After a very frustrating visit in the local Apple Store, where they told me nobody has ever heard of this problem before and that it must be a hardware problem, I called Apple Care today - and finally, after 3 hours on the phone, we could solve the problem. So maybe, it helps some of you as well by doing the following:

Start your Mac with safe boot into the safe mode (press and hold shift while pressing the on-button, hold it until a status bar appears under the apple). Try to reproduce the problem. If the problem doesn't occur in the safe mode, it's maybe a problem with the launch agents and the launch daemons (they are deactivated in safe mode) and the following will probably help you: Restart your Mac in the normal mode. In the finder, go to your HD > library > caches. Delete everthing in this folder (not the folder itself), do the same with extensions and compositions. Still in the library, re-name the folder "LaunchAgents" to "LaunchAgents.old", re-name "LaunchDaemons" to "LaunchDaemons.old". Re-start your mac, empty your paperbin and once again try to reproduce the problem. For me, it worked perfect: After this, I didn't had any problems, neither with ejected external discs nor with crashing. I even activated the sleep mode for the external hard disks and tried that one - no more problem. So I hope, the problem could definitly be solved and that it may help some of you as well.

To be honest, even if that works, its a freaking crazy solution. Like how many steps? How complicated? Please, fix this simple thing apple. And fix the **** disappearing cursor problem too!

(Yes, i got the holiday blues.)

By golly... that worked for me... Im dumb founded.

2BIG 6GB Thunderbolt

I had the same problem. My MiniStack external hard drive would improperly eject whenever my iMac went to sleep. It was never problem before I upgraded to Mavericks. I followed the instructions that nikrom posted and it worked. Thanks for sharing it.