Hard Drive Not Restorable.

Question

Level 1

0 points

Hard Drive Not Restorable.

My recently purchased 27in iMac came with Yosemite and everything was fine until I did the El Capitan upgrade last weekend. I then started having problems shutting the computer down sometimes and a few of my apps no longer worked. Last night I became tired of it and booted up into the recovery partition and tried to restore everything back from my time machine backup drive the day before I did the El Capitan upgrade. It started then came up with the error “cannot erase drive” and then everything froze. I had to hold the power button in to force a shutdown then restarted. Now it only comes up to the recovery partition and the hard drive does not appear in the startup disc window and it will not let me do anything to the hard drive at all to restore it. The disc utility’s erase and other buttons are greyed out except for the first aid and info buttons.

First aid will not fix it and the Info says the drive is not writable and that System Integrity Protection is off. There must be a problem when trying to restore machines from El Capitan back to Yosemite via Time Machine backups and it locks up the drive when trying to undo the new System Integrity Protection or something. Either that or my hard drive just went bad.

If the drive is not bad is there any way to unlock it and make the drive writable again? Any special command via the Terminal window or any special trick or workaround so I don’t have to take it in to the Apple store for repair? I don't have any other boot-up drive to try.

Thanks

iMac (Retina 5K, 27-inch, Late 2014), OS X El Capitan (10.11)

Posted on Oct 9, 2015 9:22 AM

Reply

Answer 1

rkaufmann87

Level 10

140,532 points

Oct 9, 2015 10:37 AM in response to w5hro

If your machine is less than 90 days old, it covered by complimentary AppleCare support. Please click http://www.apple.com/support/complimentary/ to learn about the service and to get started. If it's older than 90 days and have not bought AppleCare (STRONGLY suggested), you have a 1 year warranty. Take the machine into any Apple Store or AASP for it to be looked at. If you need help locating an AASP in your area please click https://locate.apple.com/country to begin finding one.

Reply

Answer 2

vladsch

Level 1

4 points

Oct 24, 2015 10:34 AM in response to w5hro

It is not a fluke because I have exactly the same problem with exactly the same causes. Upgraded my iMac 5k 27" Retina to El Capitan last night and started having OS hang-up issues.

Got fed up and decided to restore Yosemite back up that I did right before the upgrade. Booted up in recovery, selected recover from the timemachine backup. Got the Disk could not be erased error.

Now the disk shows up as 'not writable' and my machine can only boot in recovery. Got off the phone with apple support and they recommended I take it into the apple store.

Tomorrow at 10:45 I'll find out if I will be without my machine until the hardware is fixed or if it can be done via software.

Reply

Answer 3

w5hro Author

Level 1

0 points

Oct 24, 2015 11:09 AM in response to vladsch

Hi,

What is going on with these new iMacs with the Fusion drive is that you must erase the disk first. If you try to restore it back to Yosemite first without erasing, it will lock up the fusion drive. Part of the problem is that it's a fusion drive.

It's going to require a terminal command to start the disk erasure to get it back. That will split the drive in two parts, the flash drive and the mechanical drive part. Then you can combine the two back together again.

The problem is finding the right tech at Apple who knows the correct terminal command to start the erasure.

This has already been resolved with mine and the clean install of El Captain works fine now. They just released an update too which should fix the upgrading problem.

Reply

Answer 4

vladsch

Level 1

4 points

Oct 25, 2015 5:48 AM in response to w5hro

I didn't wait for my appointment and took my iMac in yesterday. It was an hour and a half wait but in half an hour the problem was solved. Followed by almost 15 hours of time machine restoration from my old slow Drobo.

It is exactly as you describe. It should have been solved over the phone and saved me four hours in total but I must admit that dealing with apple support has been a very pleasant experience. I rarely make use of support but in this case did not have a choice since the information was not available on line. I don't regret it.

The solution is quite simple. I made sure I took it in because you never know when I might need it again. Plus I always like knowing what goes on behind the pretty facade.

In recovery mode, terminal you need to get the UUID of the logical volume group for the fusion drive. It was easier to do with two terminal windows. One showing the list the other to type in the delete command since no copy/paste is available (so I was told, did not verify this) and you need to type in the UUID as it is displayed.

diskutil cs list

you will get something like the following:

CoreStorage logical volume groups (1 found)
|
+-- Logical Volume Group CED543A6-043B-40A4-9ED7-8E2062921651
    =========================================================
    Name:         Internal Drive
    Status:       Online
    Size:         1120333979648 B (1.1 TB)
    Free Space:   114688 B (114.7 KB)
    |
    +-< Physical Volume 79CAD092-B949-4AB7-8478-4ACF0A685DF9
    |   ----------------------------------------------------
    |   Index:    0
    |   Disk:     disk0s2
    |   Status:   Online
    |   Size:     120988852224 B (121.0 GB)
    |
    +-< Physical Volume ECAA24DB-E1EB-4ED3-96F8-A694C0EF1598
    |   ----------------------------------------------------
    |   Index:    1
    |   Disk:     disk1s2
    |   Status:   Online
    |   Size:     999345127424 B (999.3 GB)

Now you will need to delete the CoreStorage logical volume group given by the first UUID by issuing the following command:

Please note that the following command DOES NOT prompt for confirmation, if I remember it right. So don't try it just to see what it does unless you really mean to blow away your fusion drive data.

diskutil cs delete CED543A6-043B-40A4-9ED7-8E2062921651

The fusion drive at this point will be seen as two separate drives but the fix for this was prompted by the installer. I think that Disk Utility app in recovery mode can handle this too.

Reply