OSX: fixed the invisible issue of recovery HD after 10.10 Yosemite Developer Preview 2 was installed.

OS X 10.10 Yosemite Developer Preview 2, hereinafter referred to as 10.10dp2. After installation, 10.10 of recovery disks (recovery HD) may be invisible. This is because of a setup error. Next we will use a more intuitive method to solve it.

This is the startup option after the fix, where the recovery-10.10 is displayed

Clear

First, enable the Debug menu of the disk tool.

You can run the following command to start a disk:

defaults write com.apple.DiskUtility DUDebugMenuEnabled 1

Then run the disk tool again. The debug option appears in the menu bar.

Show each partition in disk Tool

Open it in the menu, as shown in the following figure:

Load the 10.10 recovery HD Partition

I installed it on a partition named mac3, so the 10.10 recover HD should be the one after mac3. Select it and load it in the toolbar. See the figure below:

Looking at the figure, you may be confused about this stuff, what is x.10dp2-> mac3. Next blog will explain it again.

Run Command repair

Copy the following command and run it on the terminal:

sudo bless --folder /Volumes/Recovery\ HD/com.apple.recovery.boot --bootefi /Volumes/Recovery\ HD/com.apple.recovery.boot/boot.efi --setBoot

When the terminal asks for the password, enter the password of the current Administrator.

Okay. Restart and press the option key. You can see recovery-10.10.