External USB Hard Drive not showing up, after Yosemite update

I made new tests with usb3 Western digital my passport 1to / macbook pro / OS X El Capitan :

The goal is to check if Apple bring solution with El Capitan version.

Init :

1. two exfat partitions P1 and P2 with many data

2. connect usb drive to the macbook pro.

3. partitions are mounted

Test 1:

1. Properly eject usb drive

2. connect usb drive to the macbook pro.

3. partitions are mounted after several seconds.

Test 2:

1. Disconnect without ejecting usb drive

2. connect usb disk to the macbook pro.

3. partitions P2 are mounted after ten minutes (more data you have, more time you are waiting for).

Sometimes :

1. connect usb disk to the macbook pro.

2. partitions are never mounted

There is no apple solution.

Connect usb disk to a PC / Microsoft Windows : partitions are mounted.

make a check drive to repair disk

disconnect usb drive from PC.

connect usb drive to the macbook

partitions are mounted after several seconds.

I'm waiting for a apple solution. Today, i need a PC/MS Windows when my macbook failed to read my usb drive.

I had a compact flash drive connected through a USB2.0 reader directly to my iMac. This used to work fine with Mavericks, but fails to mount with Yosemite. When I plug the USB cable into a USB 2.0 hub and then into the iMac it mounts perfectly under Yosemite. It seems that forcing the USB hardware to a slower data rate makes it compatible with the new Yosemite driver.

I found that OSX was silently running `fsck_hfs` in the background attempting to repair my TimeMachine external USB drive after upgrading to Yosemite. If I force quit the process, OSX informs me that it was unable to repair my external drive, that its mounted in read-only mode and i should back it up immediately. Because its a 1TB external USB2.0 drive, fsck_hfs is going to take forever, so in the meantime, it appears as if OSX does not recognize the drive. It would be great if OSX would notify me it was attempting to repair the drive, rather than doing so silently and making it appear as if the drive was invisible.

That worked for me! Thanks!

Hey mate,

Thought I'd hep out if it's not too late. Passport Drives won't show on you Mac without the WD Driver and Software installed on your HD. It requires a WD PassWord to unlock it in the finder. Same problem I had, installed and now working for me.

I have the same problem, a 1TB WDC drive which won't connect to my Macbook Pro 2010. I can force it to mount using Disk Utility, but it's not very convenient. This is the disc I use as my Time Machine backup and it's worked fine for a couple of years until now.

I know this is quite an old thread but this happened to me today. Putting in my USB and didn't show up in finder under devices...where it normally pops up. I was like huh? Pulled out put back in (disconnected incorrectly message came up), still not showing up. I restarted computer. Still same problem.

Boy did I feel silly....when I hovered my mouse near "device" area....magically an icon that said, "show" popped up in grey. I clicked it and it appeared. So apparently, you can hide this...and it happened. Not sure how, but it was in hide mode.

I am a newbie to mac, so perhaps i am the only one that fell for this...but thought it would be useful for the few that might not know about it.

OS X El Capitan 10.11.3 macbook air, mid 2013 purchase

Cheers

Plugging the external HDD into the USB port on my keyboard is the only fix that worked for me. MacBook Air recognised the drive straight away. Thanks didigs!