Create a bootable USB drive from a DMG file on Windows

Question

A Mac machine needs to be reformatted with Lion. I backed up the Lion dmg file when I purchased it via the Mac App Store.

I now need to create a bootable USB drive from the DMG file but I need to be able to do it in Windows, preferring open source or at least free options.

How can I do this?

Answer 1

Use TransMac, which has a 15-day trial period and works flawlessly.

1. In the left pane, right click the USB Drive and select Format Disk for Mac

2. In the left pane, right click the USB Drive and select Restore with Disk Image

3. Point to your .dmg (or choose All Files to select an .iso) file and click Open.

It will take a few minutes depending on size of .dmg and speed of USB drive, but once done you can pop it into your mac, hold down the option key when turning on the mac and choose the USB drive.

Answer 2

TransMac worked for me, but first you need to partition your USB drive with GPT. It will not work if partitioned as MBR. diskpart on Windows can do this:

diskpart
DISKPART> list disk
(Find the disk number)
DISKPART> select disk 2
Disk 2 is now the selected disk.
DISKPART> clean
DiskPart succeeded in cleaning the disk.
DISKPART> convert gpt
DiskPart successfully converted the selected disk to GPT format.
DISKPART> create partition primary

Answer 3

As far as I know, the only way to properly create a bootable Lion disc/disk is to use Disk Utility on a working Mac. However, the other option is to use a Virtualbox VM to run OS X temporarily (scroll down for that info).

On a Mac

The guide from lifehacker:

1. Download Lion from the Mac App Store. The installer should show up in your Applications folder.

2. Right-click on the installer and hit "Show Package Contents". Navigate to Contents > SharedSupport and look for a file called "InstallESD.dmg".

3. Open up Disk Utility and drag the DMG file into the left-hand sidebar. If you're burning it to a DVD, insert your DVD, select the disk image in the sidebar, and hit the "Burn" button. Skip down to the last step to use it.

4. If you want to burn Lion to a USB flash drive, plug it in and click on it in the left-hand sidebar in Disk Utility. Go to the Partition tab and select "1 Partition" from the dropdown menu. Choose "Mac OS Extended (Journaled) on the left.

5. Hit the Options button under the partition table and choose "GUID Partition Table". You'll need this to make the drive bootable on a Mac. Hit the Apply button when you're done to format your drive (note: it will erase everything on the drive).

6. Click on the "Restore" tab, choose the InstallESD.dmg file as the source and your flash drive as the destination. Hit the Apply button and it will create your bootable USB drive.

7. Reboot into OS X and hold the option key when you hear the startup chime. You can boot into your DVD or flash drive from there.

On a PC

I know this works with Snow Leopard, but I'm not sure about booting Lion in Virtualbox. My suggestion is:

1. Acquire a Snow Leopard iso image

2. Use this guide to convert the Lion dmg into an iso

3. On Virtualbox click "New"

4. Choose OS as Mac OS X and click on 64bit or 32 bit (depending on your system) Snow Leopard
5. Choose VDI as storage and click next
6. Click on Dynamically Allocated space
7. Give 4096 MB of Ram for optimum performance or you can also give 2048
8. Once finished click on the Virtual OS you just created and click on settings.
9. Go to storage and click on the disk below the vdi storage.
10. Click on the empty disk button on the right side of the window.
11. Choose the .iso file you converted earlier.
12. Just click ok and start the Virtual OS