External USB Hard Drive not showing up, after Yosemite update

Forget CD-Rom Drive problem.... some disc works well, others don't... Original, copies, music, video, data.... totally random..

If some of you have this problem, check with different disc formats.

Hi guys

I had the same issue

Disk Description : Samsung S2 Portable Media
Total Capacity : 1 TB (1,000,204,886,016 Bytes)

Connection Bus : USB
Write Status : Read/Write

Connection Type : External
S.M.A.R.T. Status : Not Supported

USB Serial Number : 00000011E0931050141B
Partition Map Scheme : Master Boot Record

The disk appeared in disk utility. After ejecting it from inside disk utility, disconnecting and the reconnecting, I was able to access the contents.

After disconnecting it again from Finder and reconnecting, the disk didn't show up.

Quite an improvisation!

I was having the same problem with my iMAC not recognizing my WD My Passport external drive. I called Tech Support and the first tech rep could not fix my problem. He finally referred me to a senior tech rep and this is what he told me to do to fix the problem:

1. Turn off my MAC

2. Unplug the MAC. He said that after installing a new operating system this is what you have to do to fix a problem like this.

3. Unplug all of my USB connections including, of course, the external drive not being recognized.

4. Wait 30 seconds.

5. Plug in the MAC and turn it on.

6. Plug in the external drive only to the USB port.

7. Open Finder and there it was!

I hope this helps everyone.

C Palise

Nope, didn't fix mine. Jr tech rep says he can't fix the problem. Sr. tech rep says restart your computer (that's what all these steps amounted to). So I restarted my computer four times tonight. The computer gods must be laughing at me.

Tried Kumquat2012 unplug theory. And it works...UNTIL my mac sleeps. Upon awakening, the external disks have been improperly ejected and are gone. No joy in external disk land.

+1...

to be noted : right after upgrade to Yosemite, I was able to launch and use all my external DD. now, anyone.

Added to my speaker problems, it's coming really frustrating...

Hey everyone.
So the same thing happend to me. I have and old macbook pro (aluminium 2007) and I always used there my external usb hard drive WD "My Passport", the drive works and it still works when I upgraded it to Yosemite.

I just bought an iMac retina and when I plug the drive nothing happens..
I tryed to update de firmware, install and reinstall drivers and WD smartware bla bla bla and nothing.

I switched the usb ports and still nothing happend.

BUT GUESS WHAT?? I connected the drive through my keyboard usb entry and it worked!

I was quite shocked.. How is this possible?

This means that the usb ports of the iMac are havving difficulties recognizing devices. This is ******** when you work with sound and video and your hard drive isnt working. But well, try it out, if you havent a wireless keyboard.

I tried it with an external USB hub and with my old wired keyboard--also tried both USB 2 and 3. I suspect your theory is correct, but unfortunately, it didn't work for me. Based on your and Kumquat2012's posts, it seems that the problem is easier to resolve with an iMac, though I'll reserve judgment on that until others weigh in. Meanwhile, I see this thread has passed 6,500 views. I wish someone from Apple would just say, "We know about the problem and are working it."

I have the exact same problem. The fixes mentioned through this topic don't work for me, either. Apple, help already. Please.

I figured I'd chime in because I'm having the same issue. 2010ish iMac, WD external drive. Initially after the Yosemite upgrade, my drive would show up and then disappear when the cpu would sleep. Now it won't show up at all. #sadfacebecomingmadface

Okay, I followed r3xsy's instructions (downloaded and installed the NTFS driver from Seagate). Then I unplugged all of my USB devices. Unplugged the mac from the wall. Plugged in the Mac to the wall then started. Then unplugged my external from its power source. Replugged in the external into the wall then plugged into the Mac. SO far, it is working, even after sleep and awakening. ONE ISSUE...I cannot copy a file from my Mac drive (SSD) to the external drive.

I have the same problem since i bought my iMac 27 Retina.

Gents, I made a fresh new installation of Yosemit. It means

1. Download Yosemite image from AppStore

2. Backup all personal data

4. Create USB installation

5. Restart the system using Alt key, enter to disk utility and delete Hard disk image because if not, reinstall process really don't delete the information.

6. Install Yosemite.

That works for me.

good luck

Hello,

I had a similar problem with a Seagate external HD which would not mount with Yosemite and could not be "repaired" by disk utility.

I simply ran Onyx, which is an excellent maintenance and repair freeware which I have been using for years, and the problem was fixed.

No hassle.

Good luck

I tried all suggestions from Apple support but none of them worked.

I then decided to run Onyx, an excellent maintenance and repair freeware, and the problem was fixed.

Also fixed some minor problems like keyboard language recognition which had switched back to QWERTY at startup whereas it is an AZERTY. Not that easy to enter your password unless you are used to using both and remember which keys correspond...

Easy, fast and straight forward.

I strongly recommend this utility.

Good luck