Q: Yosemite ejects external drives

I haven't experienced an injection of my drive in almost 2 weeks.

But just now, it happened for the first time while I was actually working on my iMac, vice overnight. And less than 15 minutes after having last accessed the drive.

And I haven't ever had this drive indexed under Spotlight.

I had older WD external drives. Updated to Yosemite (in April I think, 2015), and the drives were no longer supported. SO I bought 4T WD (MyBook), properly formatted, saved files. It was working fine. I got a second WD (My Passport, Ultra 1T). Bothe were working fine in late May. I didn't log in for about 3 weeks....

Today I logged on and suddenly neither drive works. My system loads My Book to desk top and shuts it down. Tried turning off Spotlight. Tried Energy Saver...

Worse with My Passport - it started to do something - but didn't even show up on screen, a RAID error popped up on screen and it shut down.

Nothing has worked. I have irreplaceable video files, which I could briefly see are still on My Book (This IS my back-up).

APPLE what the H---- is going on with Yosemite. Clearly I am not the only one who has developed this problem...

(Yes, FYI. Mac is Late 2009)

I'm going to try this with my Verbatim external drive. To be honest, in all the years I've used Macs I never checked out Spotlight in the system pref. Thanks for the detailed explanation of excluding the drive. Keeping my fingers crossed that tomorrow morning my drive will still

After struggling with this problem for months, something very strange happened: I had to do a hard reset of my modem and router (which I have done several times in the past several months). I moved the location of the router so it was located about 24" from the modem, rebooted the Imac with the external drive attached, and the external drive hasn't shut down once when the computer was put to sleep. No more messages that the hard drive was improperly

ejected. I have no explanation, and there doesn't seem to be a logical explanation for the hard drive not shutting down when two pieces of hardware were moved further apart from one another. All I know is it changed things and all is well.

We all just seem to be circling the drain here. After reading your post I immediately COMPLETELY disconnected from the internet (and physically). I STILL can't sleep without improper ejects.

I have tried everything suggested on here to no avail and struggle to get the IMAC to recognize the disks without either shutting down fully or changing ports. For a top of the range expensive piece of kit this is just not good enough - oh to have the clout of Tailor Swift and get Apple to act

This problem has become chronic – 9 - 10 - 11 - a dozen times a day and is MOST frustrating.

Please Apple!?

A SOLUTION must be coming along? It CAN'T be good for my external – OR for my new iMac!! 

ONE DAY LATER after 3 weeks of this:  External drive no longer mounts!!!!

This is also an issue for me. I've tried every suggestion on this thread and none of have worked. Has anyone been into an Apple story to have this looked at?

Try ALL of the above until you find the magic combination for your hardware/software configuration.  After thousands of people have reported this problem for a l_o_n_g  time Apple still has no clue as to solving it (check the many, many postings regarding external drive rejection).  Prepare for time-wasting trial and error.  Oh, Apple will not let you return to an earlier OS to escape the Yosemite curse.  You're stuck.  Weep.

PLEEEEASE FIX THIS!!!!!!!!!!!

Heeeeey Appple what a ....going on!!!!????? I am waiting to install yosemite untill yesterday., because i heard its very bad osx (as Mavericks)....i installed yesterday, but for WHY!!!!!??????? I have 22TB thunderbolt drives and i cant use it, i cant work, because they always unmounted themself randomly!!!!!! How do you think it!!!!! This is a 10.10.4!!!!and el capitan is coming , but the 10.10 osx is not useable!!!!! When do you FIX this issue!!!!!!!?????????? its a SHAME!!!!!!

I set my new iMac to never sleep (thus defeating the purpose of an always on, energy efficient computer) - power supply failed 1 month out of warranty - a $300 repair. Thanks Apple. I've tried Jettison and Mountain apps but they don't work with all my drives. Apple Inc, with all your pots of cash, please fix existing bugs before adding in new ones. Yosemite is a calamity and beta releases are of no interest to me. As a paying customer I should not be the one doing the leg work of reporting bugs (which I did, by the way, and like thousands of others here, received nothing in return). Fix your shizzle.

Just had this issue started with me with the new update... wifi issue not fixed yet... horrible experience with your machines for the past year.. get your head out of you @£$@£ and fix these issues.. I didnt pay all that cash for this kind of behaviour.... stop fiddling with that stupid watch and get back to work

I've never BEEN so disappointed Apple!!  MY brand new mac CAME WITH Yosemite.

NOTHING but this same same same trouble: involuntary sleeping, ejecting, etc, etc, etc...

Steve is rolling over.

PLEASE DO SOMETHING!?!!