Preparing the USB installation drive
Using Disk Utility on a Mac

To prepare your USB drive with this method, you'll require:

  • A Mac running Mac OS X 10.4 or later
  • An 8GB or bigger USB flash drive formatted as HFS+ with GPT-Scheme(which will be fully erased - so backup your data)

A USB installer drive with GPT partition scheme is used to setup Intel-based Macs. Old PowerPC-based Macs need a different method.

1. Download the OS X installer DMG disk image

Download the DMG disk image of the bootable OS X installer drive for your selected Mac OS X version.

The filename contains has an ending in _diskutil.dmg and it's description says, that it's specifically meant for restoring to a GPT/HFS+-formatted partition using "Disk Utility"

2. Check and format your USB flash drive

Ensure you have a 8GB or bigger flash drive.

If it currently isn't formatted as HFS+ with GPT-scheme (most likely it's formatted as FAT32 with the MBR scheme from the factory) format it using Disk Utility:

  1. Select the drive itself on the left-hand pane.
  2. Choose the Partition tab.
  3. Select "1 partition" from the Partition layout drop-down menu.
  4. Click Options and select GUID partition table.
  5. Select Mac OS Extended (Journaled) from the format drop-down menu.
  6. Click Apply to format it

Now we are going to write the image to the USB flash drive.

3. Write the image to the flash drive.

Using Disk Utility, write the downloaded DMG disk image into the HFS+ partition of your flash drive:
  1. Switch to the Restore tab in Disk Utility
  2. Select the DMG disk image as the source by clicking on Image
  3. Drag the the HFS+ parition on your flash drive (not the drive itself!) from the left hand pane into the Destination field.
  4. Click Options and select GUID partition table.
  5. Click "Restore" to write it to the flash drive
  6. Click Apply to format it
This process may last half and hour or longer, depending on the write speed of your flash drive.

4. Verify and safely unmount it

Use Finder to verify your newly created installer drive, which should offer a program Install Mac OS X or similar. Safely unmount the drive by clicking the Eject symbol in Finder хостинг