Problem installing Yosemite

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Problem installing Yosemite

Hello. I have a problem and a doubt with the installation of Yosemite.

It all started when I created Bootcamp (290GB for Mac HD, and 200GB for Windows 7); I installed Windows 7 and a lot of programs but when I tried to return to OS X, it would boot Windows instead. What happened is that the EFI partition doesn't exist anymore and the "Mac HD" partition appears as disk0s1 (which I assume is the reserved partition for EFI, but size is 290GB). The thing is that the only way I could manage to enter and install Yosemite is through Internet Recovery. I want to install the OS in an USB disk to try to recover the user data that's in the 290GB partition (the one appearing as disk0s1). So when I click on Reinstall OS X, the available partitions are: 20GB (The USB), BOOTCAMP and SYSTEM RESERVED (which is, I assume, the mini partition that Windows creates). The one where "Mac HD" should be (290GB), doesn't appear.

So I've got some questions:

When I installed Windows, could the system re-write on the Mac HD partition and turn it into a 290GB EFI?

If I proceed to install Yosemite to the 20GB USB drive, will the installer overwrite the 290GB and delete all data in it to create a valid EFI partition?

Why the 290GB is invisible? Maybe because it is encrypted or...?

I need to recover the user data, is there any other way to access the 290GB partition? Windows won't show it in Explorer, although it appears in Disk Management, and I tried with I Ubuntu DVD but the partition won't appear.

Please, some who can help me with this.

Thanks in advance.

Cheers.

MacBook Pro with Retina display, OS X Yosemite (10.10), Bootcamp, EFI partition

Posted on Aug 12, 2015 1:04 PM

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Answer 1

Kappy

Level 10

362,017 points

Aug 12, 2015 1:15 PM in response to InF3rN0iD

When you formatted the Windows partition while installing Windows, you apparently formatted your OS X partition as well. The OS X partition is gone. To put Humpty Dumpty back together you will need to repartition the drive, reinstall OS X, then create a new Windows partition on which to install Windows. I'm not sure how you can recover your data at this point because you will need software that can read the data and copy it to another drive.

Install OS X Using Internet Recovery

If possible backup your files to an external drive or second internal drive because the following procedure will remove everything from the hard drive.

Boot to the Internet Recovery HD:

Restart the computer and after the chime press and hold down the COMMAND-OPTION- R keys until a globe appears on the screen. Wait patiently - 15-20 minutes - until the Recovery main menu appears.

Partition and Format the hard drive:

Select Disk Utility from the main menu and click on the Continue button.
After DU loads select your newly installed hard drive (this is the out-dented entry with the mfgr.'s ID and size) from the left side list. Click on the Partition tab in the DU main window.
Under the Volume Scheme heading set the number of partitions from the drop down menu to one. Click on the Options button, set the partition scheme to GUID then click on the OK button. Set the format type to Mac OS Extended (Journaled.) Click on the Partition button and wait until the process has completed. Quit DU and return to the main menu.

Reinstall OS X: Select Reinstall OS X and click on the Install button. Be sure to select the correct drive to use if you have more than one.

Note: You will need an active Internet connection. I suggest using Ethernet if possible because it is three times faster than wireless.

This should restore the version of OS X originally pre-installed on the computer.

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Answer 2

InF3rN0iD Author

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Aug 12, 2015 1:22 PM in response to Kappy

Thanks for such fast response. Do you know if I install Yosemite in the USB will the installer touch the internal disk for creating any partition?

Cheers.

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Answer 3

Kappy

Level 10

362,017 points

Aug 12, 2015 1:27 PM in response to InF3rN0iD

You can install OS X on any disk without affecting any other disk attached to the computer. When the installer runs and you click on the Install button you will have an option to select the target disk by clicking on the link below the default disk labeled, "Show other disks."

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Answer 4

InF3rN0iD Author

Level 1

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Aug 12, 2015 1:29 PM in response to Kappy

Thanks, Kappy. I will do it while I'm having my fingers crossed.

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