External USB Hard Drive not showing up, after Yosemite update

I corrected this problem by finding this reference for Seagate - it fixed it right up. Basically the original formatting from the factory isn't compatible and you have to reformat to be compatible with the mac

http://support.seagate.com/kbimg/flash/213059/213059_EN.HTML

Ive used the FREE NTFS driver for Mac OS from here: http://sourceforge.net/projects/ntfsfree/reviews

and the Tuxera Paid for version (very easy to install, and works with all OSX including Yosemite

http://www.tuxera.com/products/tuxera-ntfs-for-mac/

I have no problems with NTFS drives on OSX.

After you install it, and look at System Preferences

Click on the Tuxera Icon and you can change the settings

I've run the free version, but not since just buying Tuxera. There are discount coupons for Tuxera just type in "Tuxera Coupon" in google and check them out. Don't click on a site, however, until you've installed some virus checking software. I use Avast and Avira for the Mac (Free Versions) and installed the associated Browser items in FireFox to indicate "safe sites" from those known to spread browser help objects, and other unwanted items.

Then when you see a site after using Google Search, the ones with Green Checkmarks are presumably safe, so far so good.

This is what shows in the browser with these add-in items.

Click on the green arrow and see this

Hope this helps.

Jeff

i have this issue also

So have we established that Apple have butt-f*****d us?

I have a Western Digital 2TB USB hard drive that I use to back up my MacBook Pro, but also use to store a huge library of RAW format photos from the past decade of travelling and another library of digitised family videos. Since upgrading (hah!) to Yosemite, nothing.

Are they lost forever, or do I go out and buy a PC and give up the Apple experiment as a bad job?

tried a bunch of other stuff in this forum that didn't work, so just wanted to let everyone know that this worked for me: https://www.youtube.com/watch?v=R-2NCRcylK0

The video is pretty much unnecessary - just install the 3 free programs listed in the youtube description. Finally worked for me!

I finally gave up on my windows 7 computer. Cannot even get it to boot up and tired of fixing the viruses. I bought an IMAC and I am trying to down load all of my pics etc from the old hard drive. it is a sata drive from a Gateway. I have it connect to the IMAC through the USB port. Like everyone else it shows in disk utility but not in finder. The thing I am questioning is if my drive is exfat. The IMAC show it as exfat in disk utility. I thought the only ones having issues were NTFS formatted drives. How can I confirm if it exfat and should I still be having the same issue?

The problem is NOT only with NTFS volumes. I have the same problem with almost any USB-connected flash drive, including Apple iPod Shuffles (two of them, one of them bought brand new from the online Apple Store in the past month). Sometimes they mount correctly, sometimes they don't. When they don't, the only reliable way to get them to mount is to reboot the computer (mid-2011 iMac). Makes me wonder if Apple hired some ex-Microsoft coders to work on the USB subsystem in OS X.

A few minutes ago I upgraded to the latest 10.10.2 Yosemite. Time will tell if the issue has been fixed yet.

Thanks. I just did the same update and no luck

I've had exactly the same problem. Plugged in my Seagate hard drive and isn't showing up. Tried everything (mounted, disk repairs, restart etc) but nothing has worked. I had this trouble with my college's Mac desktop that isn't on Yosemite so it may be my hard drive, however this isn't helpful a day after my college work was due in 😟 Hopefully Apple will find a solution to this problem soon!

This started happening to my brand-new rMBP a few days after getting it set up. I have a USB3 external HD for use as a Time Machine backup, and the computer now refuses to recognize its existence. The worst is when I don't unplug it before the computer goes to sleep—OS X complains about not unmounting the drive properly, and things degrade until I need to power cycle the machine, as it locks up while attempting to reboot. Absolutely pathetic—you'd think that the ability to recognize USB drives would be part of Apple's test procedure.

I just spoke to apple service and the gentleman said it was the first time he received a call about any issue with Yosemite and external drives. He is going to have a senior person call me back tomorrow. I showed him this thread when he removed into my computer.

I had this problem with a brand new 5k iMac and brand new WD My Book Studio. Whether these steps will solve the problem for everyone I don't know but it solved it for me. Disk was seen by the system report in About this Mac but wouldn't mount. Steps

1. Open Disk Utilities - The external Disk is seen by this app

2. Ejected the disk through the button in utilities.

3. Unplugged the disk from the USB connection

4. Replugged it in again.

5. Pressed the mount button on Utilities and it mounted!

I tried to reproduce this with my malfunctioning Iomega Time Machine drive but it keeps disconnecting and reconnecting. Anyway it worked with the new drive.

Hope that helps some experiencing the same issue.

I just tried this with a shiny new Apple iPod Shuffle. No luck.

I also tried it with a Garmin Nuvi 760 GPS. The "internal" flash memory in the GPS would not mount. The "external" SDHC card in the slot on the side of the GPS mounted just fine (without having to do the Disk Utility eject/mount operation). The "external" SDHC card in the slot on the side of the GPS does not always mount, but it seems to mount more reliably than the "internal" GPS flash memory..

Note that both of these devices are flash memory, not rotating hard drives. One of them is an Apple device.

As far as I can tell, all of the supposed solutions posted on the discussion forums are just random luck. Apple has screwed up the USB support in Yosemite and they need to fix it.

The only reliable way I've found that enables all external USB devices to mount properly is to reboot the machine. In my case, I never want to reboot my main machine, which is my iMac. So, I usually reboot my Macbook Pro and connect the GPS to it so I can pull the track files off of it (those files are on the "internal" GPS flash memory). So far, rebooting the machine restores proper USB functionality 100% of the time -- but only temporarily.

Mid-2011 iMac and Early-2009 Macbook Pro, Yosemite 10.10.2 on both.

So.... I found out that the computer I bought from Best buy was old stock updated with Yosemite. I exchanged it and bought a new one that came with Yosemite. It now recognizes some of the drives that it did not before. I still cannot get it to mount my exfat drive. I also cannot get it to recognize my Samsung Galaxy 3 phone at all. Will not even show in disk utility

Same problem here. My Seagate Momentus 5400.6 worked perfectly well on my old 17" MacBookPro - Mavericks. The moment I went to new machine (15" MAcBook Pro Retina Display with Yosemite, external drive no longer recognised.