Hard Drive won't mount in Yosemite

I have nearly the same problem. I use a G-Tech RAID 0 drive as my boot drive, and a separate G-Tech G-Speed Q drive for my Time Machine backup. This setup ran flawlessly under Mavericks. Since upgrading to Yosemite on my MBPro (Retina 15" - late 2013), I cannot get my system to properly mount all drives. The system will boot and run, but is MUCH slower than under Mavericks. Also "beachballs" after waking from sleep - even though the "sleep drives" option has been set to "never" - also get occasional "beachballs" when working under certain apps.

Most significantly, while my Time Machine drive does mount and display properly, my boot drive and other attached drives do not mount properly. Drives do not show on desktop or in finder, though they do show up in Drive Utility. While my Time Machine does seem to mount properly, I cannot access any pre-Yosemite TM backup. All files are available and accessible when I access the drive directly without the TM GUI, so I don't think the OS upgrade damaged drives or files. To help troubleshoot, I attached the same drive array to a machine running Mavericks, and all drives mounted and performed as they should.

Anybody who has had a similar problem gotten to the bottom of it?

Oh, I forgot to add ... after update to Yosemite, not even my MBP's internal installed SSD mounts or displays properly. Just completed permission repairs on all disks in my system - still NO external drive, save for my Time Machine drive, mounts or displays properly. UGH. Maybe it's time to revert to Mavericks.

I have read that if you turn Spotlight off you will have no problems. Open Spotlight, choose "privacy", click the "+" at the lower left and add what you do not Spotlight to search. Worked for me. I have 2 internal Seagates formatted OS X journaled in an external case. 🙂🙂

I had this issue too. I made one last Time Machine back up on my WD external drive of my Macbook 2008 before clean installing Yosemite and transferring the computer from my use to my husband's and daughter's (I just got a new MacBook Pro for Christmas). After the OS change, the external wasn't mounting as described in numerous places on the support forums. I had another Time Machine copy on a Seagate External so I wasn't worried about losing what was on the WD external and just wanted to erase it to start it as a Time Machine of the newly set up computer. Followed all the tips on this thread (Re: Time Machine disk not mounting) to no avail. But this worked for me so I could mount it and Disk Utility could erase the WD external. Be sure to heed the warning in the comments about SSD if you have a Trim Enabler. I don't have an SSD so didn't need to worry about it. Just thought this may help anyone who is continuing to experience the problem of Time Machine on an External drive not mounting after upgrading to Yosemite.

I have some of the same issues but I have also lost data due to this.

At first it was my old LaCie d2 firewire drive that didn't mount. It started about two weeks ago. After a few attempts hot swapping it I got it mounted and tried repairing it with Disk Utility. Disk Utility warned me that the drive was faulty and could not be repaired. Since it was a pretty old drive I began backing up the recent files, but the drive disappeared and my new MacBook Pro 15" Retina blacked out and restarted... I've been trying to get the data out ever since with no luck. But this might be the old drive wanting to have it's peace — I don't know.

But last week I was helping my brother in law with moving old data from his Hitachi external USB drive to his Mac after clean installing Yosemite. This drive was extremely slow and the spinning beach ball appeared again and again. From successful experience in earlier versions of OS X I repaired the drive in Disk Utility which, also here, warned about a faulty drive and gave us head aches with getting out the data.

Last example is my girlfriends Samsung external USB drive. Same issue, her MacBook Air running Yosemite. Trying to format it, it stalls halfway through, even in the fast erase settings. Mount problems too.

This made it clear to me that it can't be three cases of faulty drives, but must be Yosemite having "slept in external drive class".

Apple, please fix this quick!

Hi,

Just wondering where i find spotlight please?

As damon242 said:

damon242 wrote:

I have read that if you turn Spotlight off you will have no problems. Open Spotlight, choose "privacy", click the "+" at the lower left and add what you do not Spotlight to search. Worked for me. I have 2 internal Seagates formatted OS X journaled in an external case.

The Spotlight settings described above is found in System Preferences.

Apple doesn’t routinely monitor the discussions. These are mostly user to user discussions.

Send Apple feedback. They won't answer, but at least will know there is a problem. If enough people send feedback, it may get the problem solved sooner.

Feedback

Or you can use your Apple ID to register with this site and go the Apple BugReporter. Supposedly you will get an answer if you submit feedback.

Feedback via Apple Developer

Ok.

I have sent Apple feedback regarding this issue, hope more people will do the same.

were you able to solve this problem ? I have a WD 1 TB passpot. I had 5 partitions in it with ex fat , journaled . It was all working fine on mavericks. I updated to yosemite and it doesnt mount. Just shows as 1 TB WD drive in disk utility.

any solutions as now I just upgraded to yosemite and am experiencing this problem

I no longer have mounting problems. Even my WD My Passport Ultra mounts from a USB 3 port on my monitor (as opposed to a direct connection to the computer).

so how did you manage to solve this? Just by using your monitors usb?

I tried plugging it into a windows 8 machines , still didnt work. Tomorrow I plan to use it on a lion booted machine or again reinstall mavericks to see if it works fine.

open disk utility and check if its there, if so repair the disk and disk permissions

also try resetting the smc Intel-based Macs: Resetting the System Management ... and pram How to Reset NVRAM on your Mac - Apple Support

I assumed that Yosemite updates had fixed my issue. Can't remember if I erased the WD Passport (which Drive Genius now says needs to be replaced because of too many bad blocks).