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

YES! This is happening here also. MacPro, powered hub, usb. Still ejects Has anyone found a fix to this. I have now lost 3 drives (1 touro and 2 seagates) to this monster. Luckily, 2 of the 3 are still under warranty.

I am beside myself here. APPLE HELP!

I'm crossing my fingers here but I may have found a solution. After turning off my imac for awhile, I turned it back on and my external was showing again. Before it had time to disconnect I went into settings and changed 'put HD's to sleep' to 'never'. So far its been a day and the drive has still not ejected. Also I still have time machine off just in case. Will report back.

I'm having a similar issue with my DROBO 5D connected via Thunderbolt.  If you look in your console, you will see that the system has done a pci reset, and then your drive drops. I have no idea why mavericks is doing this.

I am knocking on wood while I type this. I have turned OFF computer sleep and I've made it a full day without disks ejecting.

I'll report back if the ejecting starts again.

Yep, 2 days now for me. It's looking good, not sure if I should switch time machine on yet though.

Just an FYI, these drives were so damaged that I could not reformat any of the three.

I was also experiencing this issue when copying data to the drives - they would just unexpectidly eject!  Using an ICY BOX twin bay docking station connected via USB 3 to my 2013 iMac.  Mavericks.

So after trying loads of things I changed the connection cable to a USB2 and this seems to have fixed the issue for me.  Have had this set up for about 3-4 days and no issues as yet.

So its either a dodgy cable I got or Mavericks aint liking the USB3 connection

Well...I don't want to rain on your good fortune parade but all of mine are USB2 since I have an older Mac I am stuck there without buying a pci card.

I truly hope you keep your drives running smoothly.

I am of the consensus that this is a Mavericks issue and needs to be aggressively addressed. I've lost 3 drives and unable to reformat or use in any capacity. This is a HUGE issue for me and a very costly one.

The same thing started happening with my machine. I just recently upgraded to Mavericks and have a LaCie 4TB Raid as my Time Machine backup. Never had any issues with sleep/wake modes and random ejects — but now I suddenly do… Strangely enough, another 500GB LaCie drive doesn't magically eject on sleep/wake.

My current machine is a 2.2 GHz Intel Core i7 15inch MBP with 8GB Ram.

I am having the same problem.  I am using an Orrico  Dock with 4 3 TB Synnex hardrives.  I have 16GB of RAM and an Intel 3.02 Ghz Core Duo on my IMAC  This has not happened ever until Mavericks.   I am surprised Apple has not already come up with a Fix

same here, random ejectings on my 4 seagate usb 3 external drives with my late 2012 mac mini 2.3 quad i7, only started with mavericks it has to be an OS related problem. very annoying

For all you guys experiencing this problem, uncheck 'put hard drives to sleep' in settings. I know this isnt the ideal solution but has been working for me. 1 week and no ejections so far.

lol thats a no brainer son!

I will try that solution and see what happens.  Seems strange that Apple has not come out with a fix yet.  

Run Etrecheck and verify you dont have any WD software running

https://www.macupdate.com/app/mac/48217/etrecheck

EtreCheck is a simple little app to display the important details of your system configuration and allow you to copy that information to the Clipboard. It is meant to be used with Apple Support Communities to help people help you with your Mac. EtreCheck automatically removes any personally identifiable information from the output.

fsck is likely what is causing all theses occurances along with spotlight indexing.

Put your external HD into the privacy setting

launch the Spotlight preference via System Preferences, click on the Privacy Tab, click the '+' sign and add in any drives that you don't want indexed.