I installed OS X Mavericks on a external hard drive. This caused a problem I did not anticipate: I can no longer boot from the internal Yosemite installation.

How can I instruct OSX to boot from my Yosemite installation instead of the Install OS X Mavericks container? Am I screwed?


  • If I remove the external hard drive and press the option key during startup there is only the "OS X Base System" visible.

  • In single user mode I can see the system mounting an image from inside Install OS X Mavericks.app. Full verbose startup output

  • Everything from the internal hard drive is still accessible under "/Volumes/Macintosh HD" when running from external drive. However in Disk Utility there is no Partition Map Scheme for internal drive.

  • The file /Library/Preferences/SystemConfiguration/com.apple.Boot.plist on the internal drive has no instructions about mounting the installer DMG.

  • bless --info command produces following results:

Blessed System Folder is /Volumes/Macintosh HD/System/Library/CoreServices

Blessed System File is /Volumes/Macintosh HD/System/Library/CoreServices/boot.efi

Open-folder linked list empty

No alternate OS blessed file/folder

Unused field unset

OS X blessed folder is /Volumes/Macintosh HD/System/Library/CoreServices

The solution turned out to be simple: the installer had converted my internal drive into a corestorage volume, and after reverting it back to HFS I could boot from my internal drive again.

diskutil corestorage revert /dev/disk1
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