Fusion Drive crashed, HDD not mounting

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Level 1

32 points

Fusion Drive crashed, HDD not mounting

My late-2012 iMac 27" (secondary machine) crashed hard the other day (Yosemite 10.10.3, 16 GB RAM). Now only the SSD mounts. The HDD was visible after one restart, but now is nowhere to be found. I've reset the NVRAM and SMC several times, but only the SSD is visible from the Recovery Partition. I've tried booting into Single User Mode, but it gets stuck in a loop "Still waiting for root device."

I figure if I can get both the SSD and HDD to show up, I can "fix" them with Disk Utility and reinstall the OS from scratch. All data is lost, just trying to get the 3 TB Fusion Drive operable again.

Any help would be greatly appreciated!

iMac (27-inch, Late 2013), OS X Mavericks (10.9.4), 3 TB Fusion Drive, 32 GB RAM

Posted on May 14, 2015 2:06 PM

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Answer 1

Kappy

Level 10

362,023 points

May 14, 2015 2:19 PM in response to Dana Cameron

Boot to the Recovery HD:

Restart the computer and after the chime press and hold down the COMMAND and R keys until the menu screen appears. Alternatively, restart the computer and after the chime press and hold down the OPTION key until the boot manager screen appears. Select the Recovery HD and click on the downward pointing arrow button.

When the recovery menu appears select Disk Utility and press the Continue button. If the HDD does not appear in the Disk Utility listing, then it is dead and needs replacing.

Note: Fusion Drives are created using Core Storage via the Terminal command, diskutil. If you are not familiar with what to do, then I suggest either you leave the HDD separate and not attempt to restore the Fusion Drive or take it in for service.

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Answer 2

Dana Cameron Author

Level 1

32 points

May 14, 2015 3:20 PM in response to Kappy

Yes, I've run through the steps you've outlined a few times and used the diskutil cs list and diskutil cs delete strings to try to force the it to re-recognize the internal drives. All to no avail. I'm thinking it's dead.

It's not a huge deal because I wasn't using much space on that HDD (no data lost), but it's definitely distressing to think that in less than three years it would die so immediately on me with no warning. Tech Tool Pro 7 and Drive Genius 4 were both active and had reported no problems at all.

At this point, I'm just going to try to get the SSD back up and continue using it in TDM.

Guess I should start the countdown clock on my 2013 iMac's Fusion Drive now.

Thanks for your help.

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Answer 3

Kappy

Level 10

362,023 points

May 14, 2015 4:17 PM in response to Dana Cameron

If you open Disk Utility to see if the HDD appears in the sidebar, then it could be repairable. If it does not make an appearance then it's departed. Actually, the average life of most disk drives in use is around 3 years or less, hence, why the typical warranty is only 3 years.

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Answer 4

Dana Cameron Author

Level 1

32 points

May 14, 2015 8:34 PM in response to Kappy

On my next restart, the HDD appeared and I was able to fix it and recreate the Fusion Drive. It kept failing and disappearing however, periodically citing an I/O error of some sort. The HDD, or its controller, is definitely bad. The SSD consistently appeared however. On its last solo appearance, I checked it twice with Disk Utility and installed Yosemite on it. I'll leave the drives separate for now. I might look into having the HDD replaced at some point, but I currently don't need it.

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Answer 5

Kappy

Level 10

362,023 points

May 14, 2015 9:39 PM in response to Dana Cameron

The drive is failing. The I/O errors are the sign. Get the drive replaced when you can.

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Answer 6

sabre138

Level 1

9 points

Mar 19, 2016 6:52 AM in response to Dana Cameron

I spent 2 hours on the phone with Apple Support. Then they scheduled an appointment with the Genius Bar for the same problem. When I got there they said I didn't have an appointment but would get someone to look at it. They did everything the others have posted on this thread. After waiting another hour the tech worked on it for another hour and a half and declared the drive dead. Now I have to wait 3-5 days to have a new drive installed. This is a 4 month old IMac with a fusion drive. I am not a happy camper !

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