Apple

How to create a bootable USB to install OS X

Jesus Vigo goes over the steps to create a bootable USB to install OS X 10.7-10.8 and OS X 10.5-10.6, as well as how to put multiple versions on the same USB.

With the advances in technology, faster data access (SSD), and slimming hardware footprints, legacy technologies are typically the first cuts made to get these devices thinner and lighter while making them more powerful and efficient.

Installing OS X has never really been a particularly difficult task, but try doing that on a MacBook Air or a system with a broken optical drive. Not so easy anymore is it? Even downloading the OS from the Mac App Store wouldn't do when the hard drive needs replacing or the Recovery Partition is corrupt. Luckily, Macs have a couple of options, specifically USB booting, and since most have an SD card slot, we can use those as well.

Creating a USB Installer for Apple OS X 10.7-10.8

Before proceeding, we'll need the following items to complete the process:

  • 8GB USB Flash Drive (or SD Card)
  • Install OS X Mountain Lion.app (installer downloaded from Mac App Store)
  • Apple computer with Mac App Store (OS X 10.6.8+)
  • User Account with Administrative privileges

Follow these steps:

1.     Using a Mac with at least OS X 10.6.8 installed, access the Mac App Store and download the Lion (10.7) or Mountain Lion (10.8) app installer.

2.     Insert the USB drive into the Mac and launch Disk Utility.

3.     Click on the USB drive from the left-hand menu and select the Partition tab.

4.     Click the drop-down menu, selecting 1 partition.

5.     Select Mac OS Extended (Journaled) for the format-type from the drop-down menu. (Figure A)

6.     Click on the Options button and select the radio button for GUID Partition Table and click OK.  (Figure B)

7.     Upon completion of the USB formatting, locate Install Mac OS X Mountain Lion.app (downloaded in step #1 to the Applications folder, by default). Right-click the file and select Show Package Contents. (Figure C)

8.     Navigate the file structure Contents | Shared Support and drag the InstallESD.dmg file to the desktop. (Figure D)

9.     Go back to Disk Utility and click on the newly formatted USB Drive in the menu, then click on the Restore tab.

10.  In the Source textbox, click the Image button and select the InstallESD.dmg file on your Desktop. For Destination, drag & drop the partition created on the USB drive onto the textbox. (Figure E)

11.  Upon verifying that the fields are correct, click the Restore button and select Erase from the application, if prompted to do so. (Figure F)

12.  The process may indicate in excess of one hour, but in my experience the process takes significantly less time to complete. (Figure G)

Creating a USB Installer for Apple OS X 10.5-10.6

The process is nearly identical, with a few alternate items to complete the process:

  • 8GB USB Flash Drive (or SD Card)
  • Apple OS X Install DVD*
  • Apple computer with (OS X 10.5+)
  • Built-in or USB Optical Drive
  • User account with Administrative access

*Note: Install DVD must be the original DVD from Apple and not a Restore DVD that came with earlier model Apple computers & laptops. The process has not been tested with Restore DVDs and may not yield a reliable, OS X Installer USB.

  1. Insert Apple OS X Install DVD into Optical Drive.
  2. Launch Disk Utility and click on the OS X Install DVD from the left-hand menu.
  3. Click on the Restore tab and verify that the Mac OS X Install DVD appears in the Source text box.
  4. Drag & drop the formatted USB drive partition to the Destination textbox. (If you did not format the USB drive, please follow steps #2-6 from the 10.7/10.8 tutorial above) then continue on to step #5 below. (Figure H)
  5. Upon verifying that the fields are correct, click the Restore button. Select Erase from the confirmation box, if prompted to do so.
  6. If asked to authenticate, enter credentials that have administrator access and click OK to proceed.
  7. Since this scenario requires reading data from the optical drive, it may perform slower than reading files that are located on the hard drive.

Once completed, the USB drive will be bootable and have the full installation of OS X on there to install from scratch and update systems, as needed. Remember, this being a writable drive offers some additional perks over read-only media with a few caveats as well.

Pros:
  • Include additional resources on the drive that are required by your organization, such as Combo Updaters, applications or settings.
  • Backup directories prior to initializing the HDD and/or reinstalling OS X.**
  • Include multiple versions of OS X on the same drive.**
Cons:
  • Writable means live data can be subject to accidental deletion or corruption.
  • Read/Write speeds vary wildly depending on the make/model of the USB drive. Choose the highest read and write speeds for your particular application to minimize this bottleneck.
  • Loss/theft of USB drives and any additional data, such as configurations, passwords, etc. that may be contained therein. Be careful!

**Note: Feel free to include any additional files or folders to the existing drives, so long as the original file hierarchy is not modified in any way. This is important as the OS X installer is looking for specific files at specific locations during installation. A missing, modified or corrupt file could result in an unreliable installation.

Multiple OS X versions on the same USB/SD card (Bonus)

While writing this article, I found myself in a predicament - I only had a 8GB USB drive! But luckily, I found a 16GB drive I'd lent my wife awhile back and decided to try to get the two versions of OS X encountered most frequently (10.7 & 10.8) onto the same 16GB USB drive.

And it worked! To achieve this, you'll want to have a USB/SD card capable of holding all the OSs on drive. This means about 8GB of storage space per version of OS X. The steps are identical to the Creating a USB Installer for Apple OS X 10.7-10.8 tutorial listed above, except for two key differences.

  1. Instead of selecting "1" partition in step #4, you'll be selecting a number equal to the number of versions of OS X you'll be copying over. (Ex. If housing 10.5/10.6/10.7/10.8; 8GB x 4 versions of OS X = 32GB total; 4 partitions will then need to be created).
  2. The copying process (steps #9-12) will now need to be repeated once for each version of OS X being stored.

Tip: By default, Disk Utility names the partition identical to the source "Mac OS X Install DVD" in my case. While thoughtful, if working with multiple partitions, each will have the same name making them indistinguishable from the others. To resolve this, once the entire copy process has completed for all versions of OS X, the Finder will mount them all on the Desktop. Go through each to identify which version of OS X is contained, then simply rename it to a common name, such as 10.7 for the Lion installer; 10.8 for Mountain Lion, etc. When booting to the USB/SD card by holding the Option key during start-up, the drives will mount with their new names making them easier to identify.

About

Jesus Vigo is a Network Administrator by day and owner of Mac|Jesus, LLC, specializing in Mac and Windows integration and providing solutions to small- and medium-size businesses. He brings 15 years of experience and multiple certifications from seve...

30 comments
slickworm
slickworm

Trying to re-install 10.6.8 w a stick and after I click the reinstall disk the apple logo just stays up FOREVER. Have tried redoing this several times and nothing changes! Help appreciated!

mogleybogley
mogleybogley

When I try the "restore" step, a window pops up telling me that it could not be completed because of an invalid argument. I'm making sure that InstallESD.dmg is the source and my newly partitioned storage space is the destination. Any thoughts how I may be able to fix this?

yessu11
yessu11

how to remove partition and use USB drive normally

debus
debus

Thanks Jesus!  Just what I needed.


Installing a new 1TB drive in my mid-2010 Macbook Pro.

pinteresque
pinteresque

Thanks for this comprehensive and clear explanation.  It's the only tutorial I found that led to success.  I am now installing Snow Leopard from USB as I type.

keegan720
keegan720

I keep getting this input output error message when I try to copy to the flash drive. I am on 10.5.8 trying to upgrade to 10.6  Please help me 

paradoxdrummer
paradoxdrummer

I was able to successfully create a 10.5 USB, but I am now having trouble installing with it. I replaced the HDD in an old iMac G5 with a Samsung SSD and am now trying to get 10.5 installed on it. When I boot, I can't get the computer to recognize the USB install disk I have plugged in. I just go straight to the flashing ?/OS folder thing. Any idea what could be wrong?

alenxader
alenxader

I've gotten as far as creating the bootable usb but my 2008 Macbook won't boot from it. After holding down Option, it shows the two drives, but when I click on the usb with Mountain Lion installer, the next screen is the prohibitory sign. I never get the OS X Utilities screen. Any tips? Thanks!

nivanov23
nivanov23

Hi, 

I followed all the instructions but when I try opening the installer from my USB, the installer bounces a few times in the dock then opens for a split second and immediately closes. This is really frustrating and I don't know why it's happening. I have a 2009 MacBook with 10.5.8 and I'm trying to install Snow Leopard. I tried opening it from the guest account to see if it was just user settings messing it up but that didn't help at all.

Thanks

1986mattjones
1986mattjones

Hi,  

I need to reinstall Snow Leopard, but my dvd drive isn't working.I noticed you said that for 10.5 to 10.6 you need to have the install disk. but can't I jsut do a similar method to the higher versions? I'm downloading the dmg of the install disk form a torrent site, (don't really see anything wrong with this as i've paid for it before anyway). Any idea if this will work?


Thanks

themacjesus
themacjesus

Thank You @envokedesign I appreciate the words of kindness and the update too! I haven't gotten much of a chance to really sit and work with "Mavericks".....yet. But I'm very happy to hear that the process works just the same. I'll definitely have to take some time from beta testing iOS 7 to try out OS X 10.9. Thanks again!

envokedesign
envokedesign

Awesome right up. I just wanted to confirm for anyone wonder, that this is the exact same method for installing OSX 10.9 Mavericks DP1. Yes Mavericks isn't released yet, but creating a bootable install of the developer preview follows this same tutorial above. Cheers!

kuzmicheff
kuzmicheff

I created a bootable drive from an 8GB USB drive following steps in the tutorial. I tried booting from it and running Disk Utility, and it worked fine. When I tried to install OS 10.8 on my new external SSD drive, the installation started and after some time popped up with the message saying that required package components cannot be downloaded. I could only press OK in that dialog, and then the installer quit. So does this approach work only for booting and installing OS on internal drives? Please clarify. Thanks a lot!

sparkyuiop
sparkyuiop

I have an early 2011 MacBook Pro (13 inch) and recently my hard disk failed. I had lost the original installation disks and so phoned Apple for advice. I was told that my machine was originally installed with Snow Leopard 10.6 and that I would need to purchase the disk in order to re-install it. Being an avid PC user I looked for a torrent of it to download. Not because I thought the £20 was too much money but because I wanted to get on with it there and then. Besides that I felt I was entitled to it for free as it came pre-installed on my machine anyway and was in effect paid for in the cost of the MacBook. That said I am not allowed to post any details where I got the torrents from as it is against this websites rules. I tried several torrent files of 10.6 in DMG and ISO format and tried again and again to create the USB installer on my 16GB SanDisk flash drive with no success. I got error ranging from ‘Restart your computer – kernel panic’, the Apple logo followed by the ‘Stop’ sign and various ‘input / output’ and other error messages when erasing / restoring my disk using the disk utility. I decided to try and install Mountain Lion 10.8 instead. On my first try I held the option key and turned on the MacBook and was given the option to use internet recovery after entering my Wi-Fi key. When this loaded I erased my internal disk, partitioned it with 1 partition and made sure the GUI option was selected. I then verified my disk and it was reported as being fine. I closed the disk utility and proceeded to install Mountain Lion from the main menu. After selecting the disk to install to I was informed that my computer was not licenced to install Mountain Lion and that I would need to buy it for £15! So I downloaded Mountain Lion from another torrent, mostly as I didn’t even know if it was going to work. After the 4.04GB Mountain Lion 10.8 had downloaded I put the ‘InstallESD.dmg’ on a USB hard disk (mostly for transfer speed), popped in the 16GB flash drive, held the option key and turned on the MacBook then selected the ‘Internet Recovery’ option and put in my Wi-Fi key. I ran the disk utility, erased my internal hard disk, partitioned it using the 1 partition selection from the drop down menu, renamed it ‘Mackintosh HD’ and checked the ‘GUI’ option. I then verified the disk and it was reported well. I then erased my 16GB flash disk, partitioned it using the 1 partition selection from the drop down menu, renamed it ‘Install OS X’ and checked the ‘GUI’ option. I then verified the disk and it was reported well. I then hit the restore tab, dragged my ‘Install OS X’ into the Destination box. I then pushed the ‘Image’ button and selected the hard disk containing the ‘InstallESD.dmg’ and double clicked it. After clicking the ‘Restore’ button I waited some 25 – 30 minutes for it to complete. Once I had created the USB install disk I removed my USB hard disk containing the ‘InstallESD.dmg’ but left in the flash drive and shut down the MacBook. I then started the MacBook holding the option key and this time chose the USB flash disk, not the internet option. The first time I got confused here and went back into the disk utility and tried to flash the USB to the hard disk again! What I should have done was just to select the ‘Install OS X’ from the first menu which I worked out soon after! After doing that and 25 – 30 minutes later I have a working MacBook Pro running Mountain Lion and have just updated the software with no issues. I hope this is helpful for some people. I knew nothing of installing Mac’s and spent a day and a half pulling my hair out with Snow Leopard 10.6 getting all the errors everyone else has. Just for the record, I’m now going to buy Mountain Lion 10.8 as I know it works;)

themacjesus
themacjesus

This one comes by way of a reader that pointed out Apple's official solution: OS X Recovery Disk Assistant. It's only compatible with Lion and Mountain Lion and involves downloading the 1GB .DMG and running it from your Mac. An external USB Flash or Hard Drive is required, as well. This process essentially creates a portable Recovery HD partition which is invisible to OS X but can be accessed only when booting from the target disk by holding down the option key when powering on your Mac. Source link along with detailed instructions available from Apple: http://support.apple.com/kb/ht4848 Thanks again to everyone for writing/posting your suggestions!

RockerGeek!
RockerGeek!

I've used Lion DiskMaker to create my bootable 10.8 flash drives. It only does 10.6, 10.7, and 10.8. http://liondiskmaker.com/ It's pretty sweet. I have the installation package saved to the desktop of one of the administrative iMacs in the office and when I need to create a bootable flash, I use that. Point the app to use the install files from the desktop and boom.

boucaria
boucaria

I have too many of the 8 Gig, but I use most of my practical units on the 32 Gig Sandisk Drivers ( basic and more secure ). So, should the process above cover an install on a 32 gig USB "stick" ( hate that term ) drive etc.

matt.cherniak
matt.cherniak

@paradoxdrummer You need to format your USB partition in "Apple Partition Map" style instead of "GUID" as described above. Simple as clicking on your options and changing your selection and completing the rest of the steps as described above and your Power PC will be able to understand what you are sticking in it

themacjesus
themacjesus

Hello @nivanov23, sorry to hear you're having this problem! I would try to reboot the laptop and hold down the "Option" key to enter the boot selection screen. Select your USB installer drive and try to load it that way - bypassing the live OS X environment. 

If that fails, you may wish to retry creating the USB installer using another USB just in case the drive may be faulty or have some issue with regards to the memory modules.

Best of luck @nivanov23 

themacjesus
themacjesus

@1986mattjones Hello!

In all honesty, you're mostly right! As long as you have an .ISO/.DMG of the 10.5/10.6 image, one can create the USB installer in a similar fashion to 10.7+. I only advise that users have the DVD media since those versions were released in DVD media format only and that is what most have available to them.

Secondly, and to a lesser degree. Not everything downloaded from a torrent is a clean rip. Which means the software may have been tampered with (unintentionally or otherwise) and this has been known to introduce random errors during the installation process, like errant Kernel panics.

However, if you have acquired a clean image of the original DVD, then yes, the creation process is nearly identical.

Thank You for writing in @1986mattjones 

themacjesus
themacjesus

I'm sorry to hear about the trouble you're experiencing with your OS X install. Now, the tutorial was meant for internal HDD/SSDs, but truth be told, the process should work pretty much the same for external drives as well. One thing to maybe try is to connect the external SSD to a working OS X installation first and perform the Disk Utility actions from there first, prior to actually installing the OS. Other than that, I'd double-check the OS X media to ensure that the USB install media was created properly. I mention this only because based on the error message you referenced in your post seems to indicate that there may be some files or components that did not install themselves properly onto the USB media during the copy process. Let me know if this works out for you and thank you for writing in.

themacjesus
themacjesus

Hey Sparky, sounds like you traveled the gamut from frustration to annoyance (and back) in trying to get your OS reinstalled. While I'm sorry to hear about all of the trouble you went through, I do want to take the opportunity to stress a very important point about downloading software (especially OSes) from less than legal sources. Aside from the obvious it's wrong argument, I'm not here to judge, but rather point out that many of the applications uploaded to various websites around the world claim to be "legit" or "original", but in fact, are not. The truth is that most have probably been tampered with in some way, shape or form. Either way, when we're talking about an OS - the base application which runs all the other system processes unto and including all the software which is run - you want, no, need that to be as solid & stable as possible. It's like the foundation of a home, if it's not up to code, the rest of the house may not fair well for very long before one starts to see cracks in the structure...the OS is no different! I do not advocate illegal downloading and actually go to great lengths to avoid it as much as possible, especially when there are so many great resources out there for discounted legitimate purchases - and honestly, you can't beat Apple's $20 OS pricing! Even the Server version of the OS is inexpensive compared to other vendors! But the underlying message remains the same, start of with the best foundation available when (re)installing any OS, always! This means getting it from a source where the files included have not had their internal security circumvented, tampered with or otherwise "cracked". It'll pay off in the long run, I can assure you! Thanks for sharing your story, Sparky!

themacjesus
themacjesus

I love apps, especially the ones that allow us to work smarter - not harder! With that said, it's always good to know a manual way to perform certain jobs in the event that one finds themselves truly disconnected from anything but just OS X. Thank You for bringing this to everyones attention, RockerGeek! Lion DiskMaker is an excellent app for creating bootable flash drives with OS X files in a more automated (i.e., easier) fashion.

themacjesus
themacjesus

But a 16, 32 or even 64GB USB Flash Drive works just the same! I currently have a 16GB with a split partition of 10.7 on partition 1 and 10.8 on partition 2. Just keep in mind, each version of OS X consumes ~8GB of storage space. Any available space outside of what's used for the OS itself can be utilized as storage for backing up data or storing your apps or updates. That way when reinstalling OS X, you'll have all your necessary files on one handy, portable place!

paradoxdrummer
paradoxdrummer

 @matt.cherniak @paradoxdrummer I tried doing the partition as an "Apple Partition Map" and still ended up with the same blinking ? folder. I think the problem may be that the computer is not recognizing the SSD. Perhaps I need to reformat the SSD as "Apple Partition Map"? My only other guess is that the computer can't read/write fast enough for the SSD drive.

kuzmicheff
kuzmicheff

Thank you, Jesus, for pointing out the direction for me! I prepared the external SSD drive for installation using Disk Utility in Mac OS that was running on my internal drive. So the initial part was done correctly. But then I copied InstallESD.dmg instead of just dragging it to my desktop which in fact creates a shortcut rather than a copy of the file. That was obviously where some installation components got lost. I will go ahead and redo it, and I will post an update here so that we all know that it works. Thank you for your help!

RockerGeek!
RockerGeek!

I wasn't dissing the "know how to do it for yourself" method (and frankly I enjoy that method and found this article useful). It's always good to have a plan A, B, and C or more.

themacjesus
themacjesus

You're most welcome! @kuzmicheff I'm happy to help. One thing to look out for, I recently performed an install on a USB Flash Drive myself and found that while continuing with the installation, I was prompted to enter my Apple ID credentials. This is something Apple has implemented (I believe) in Mountain Lion to ensure that users have actually purchased ML via the App Store. Now, while my credentials went through without a problem, I can see a scenario by where either the end-user does not have a purchase record for ML linked to their Apple ID or realistically, they do, however, entering the incorrect password or not having an internet connection may cause the install to proceed forward without downloading the necessary files - leading to an error somewhere down the line. Just something to check for when installing OS X on removable media/drives. Thanks again for the follow-up!

themacjesus
themacjesus

No "diss" taking at all...not in the slightest :) There's always more than one way to do something and that's the beauty of IT. There is no right or wrong way (many times) there just exist easier ways to get things done. Call me cautious or just maybe slightly paranoid, but having multiple plans to fall back on can be life savers in the truest sense. Not every solution is going to work, every time nor in every scenario. It makes me glad to hear that the article was useful! Thank you again for the input, I really do welcome the opportunity to share with other like-minded professionals!