Install Mac OS X from USB or Firewire Drive/Disk
by Andre on Mar.27, 2009, under Mac OS X, Mac OS X Server
hello pirates! 
So you found yourself with a huge .iso or .dmg of Mac OS 10.7 (or earlier). Maybe you made it yourself and lost the disc, maybe you downloaded it, maybe your DVD-Drive is broken (as every singe one of my macs turns out to be sooner than later).
On a mac: Open up disk utility, click on your usb or firewire drive and then go to the partition tab. Name your disc, in this instance we will call it Mac OS X Install.
Choose Mac OS Extended (Journaled) as the format.
Next make sure you click the options button and choose GUID (intel mac) or Apple Partition Map (PPC). Click Apply.
Now comes the fun part. In the left hand pane click on your newly named disk Mac OS X Install (After formatting is complete of course).
Click the Restore tab on the far right. Click the Image button next to the source field and choose your .iso or .dmg.
Next drag your newly formated Mac OS X Install icon (from the left pane or from your desktop to the restore field) and click restore.
If I remember correctly it will ask you for your admin user/pass.
If you get a failure at this step try to mount the image and restore from that. If that doesn’t work unmount it and try the original again. It has been flaky for me sometimes. A sure fire fix is to go to image in the menu and click “scan image for restore”. Takes a bit but lets you continue.
After it has completed eject the usb/firewire drive and take it to the mac you want to instal OS X on.
Plug in the usb/firewire drive and startup the mac. Right after hitting the power button hold down the “option” key. You will see a boot menu with your usb/firewire drive listed as a boot option. Click it and hit return. Install…
Reminder that PPC’s can’t boot from usb so you will have to use a firewire drive for this. Although I swear I have booted a Power Mac G5 from usb, its been too long to remember though.
Want to make a fully bootable usb or firewire drive of your current system that you can take with you? Or just for backup. Try:
Carbon Copy Cloner or Super Duper. Both great backup tools that are so easy to use they don’t need a post. Make sure you follow the formatting instructions at the top of this post if you want to make the drives bootable with these 2 programs.
September 1st, 2009 on 1:09 pm
Thanks! It helped me installing OS X Snow Leopard!
nice job
September 1st, 2009 on 3:22 pm
well, this erase all of the file on the usb drive? or those file still could be there? thanks!
September 1st, 2009 on 3:27 pm
bo,
Partitioning your USB drive will delete everything on it. Unless the USB drive is already partitioned/formatted GUID and MAC you can choose not to check the “erase” box in the restore process. - Cheers
September 8th, 2009 on 7:20 pm
Hi
i just installed it succesfully. Very easy.
I benchmarked it just before and just after upgrading from 10.5.8 to 10.6.
My score raised with 30% from 64 to 84 using Xbench. Supercool.
Thanks for the tutorial.
October 12th, 2009 on 6:40 am
Can you boot from USB on IMac As well?
October 12th, 2009 on 7:55 am
Dmitriy…
Non G5 iMacs YES (intel)…Never tested a G5 with USB boot but I can only guess it suffers the same debilitation that apple placed on everything else non intel.
November 4th, 2009 on 9:38 pm
All right… but aren’t there 2 install discs, plus the leopard one? how should that be handled with this method?
Thanks
November 4th, 2009 on 9:54 pm
tresvampiros…
2 install disks? mac os x has come on 1 dvd since 10.4. Are you thinking of the restore dvd’s that come with a new mac? If that is the case just partition the drive 3 times and restore each image to 1 partition. hold option at boot and choose which one you want.
May 26th, 2010 on 9:30 pm
Thanks alot man, really easy to do and great tutorial. (Snow Leopard just aint coperating with my Mac Mini so restoring to Tiger and DVD drive is dead :|)
August 6th, 2010 on 11:25 pm
Is there anyway I could do all of this on a PC?
August 10th, 2010 on 8:03 am
Austin, sorry, not that I know of. (unless you VM’ed Mac OS X)
October 29th, 2010 on 5:01 pm
nice…thanks…
saved me an unneeded trip to the store and some $ for DL DVD….
Thanks..
January 24th, 2011 on 7:47 am
how to install mac on a windows 7 pc with a usb because i dont have a dvd drive. But, I have the contents of Mac OS X Snow Lepord copied into my harddisk.
February 18th, 2011 on 4:34 pm
Ag,
you can’t install Snow Leopard on a Windows Pc without MAJOR modifications. The Pc is set to understand MS-Dos while Mac OS X is written in Unix. Also, apple locked thier software to Macs only. If you really want to check out hackintosh’s manuals but i wouldn’t suggest it.
-b.mart.95
May 7th, 2011 on 12:34 am
bmarty95: you are close… but not exactly right. The PC is not related to MS-DOS anymore, and Mac OS X is not written in UNIX. The difference is the architecture, Mac OS X is (like unix) a POSIX compliant system (that means that it follows the POSIX guidelines, while Windows is just some random thing that doesn’t follow any guidelines. Mac OS X uses the more advanced EFI for booting, while Windows still uses BIOS. BIOS isn’t bad or anything, it’s just a bit outdated (its from 1975 or so). This is the reason that Mac’s don’t like booting on PCs, but you can emulate EFI with tools like rEFIt (google it)
June 10th, 2011 on 3:09 pm
When I click Restore, I get the “Restore Failure- Could not validate source” error, and I’m confused when you say “If you get a failure at this step try to mount the image and restore from that. If that doesn’t work unmount it and try the original again.”
What do you mean try to mount the image and restore from that? How do I mount the image?
Thanks for any help on this. much appreciated
June 28th, 2011 on 6:10 am
Thanks a million. It worked like a lucky charm.
June 28th, 2011 on 6:24 am
@Nels, the dmg or iso you are using is a real mac os x installer right?
I used a dmg of 10.6 and its working as i write. it fixed my problem.
My Problem:
I had erased the hard drive completely; up to the point where the mac would show me gray screen and a fold with a question mark. luckily, i have another mac where i keep my downloads, burned copies of cds, and games, and i used a 64gbs External Hard Drive, followed the above steps and it worked.
ps,
you dont want to end up with a gray screen and a folder with a question mark; unless have a mac os x installer, not update.
August 1st, 2011 on 4:08 pm
Thanks a bunch, bro. ‘Preciated.
October 30th, 2011 on 2:53 pm
Thanks. So helpful. Just successfully ‘restored’ an old Power Mac with your help!
December 28th, 2011 on 6:08 pm
it worked for me too! this tutorial helped me a lot!
thank you!