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HowTo revert new MacBook Pro, Mac Pro or iMac to Snow Leopard

75562 Views 359 Replies Latest reply: Mar 20, 2013 10:26 AM by BigBongo RSS
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Roy Miller Calculating status...
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Aug 15, 2011 9:00 AM

Hi all,


the following instructions were provided to me by our Apple Enterprise tech, and I've successfully performed these steps on a newly purchased MacBook Pro.


Please note the following - as of 15 Aug 2011:

- this technique will work on new MacBook Pro, Mac Pro or iMac computers UNTIL Apple modifies the hardware in these computers

- this technique will NEVER work on currently shipping MacBook Air or Mac Mini computers

- this configuration of Snow Leopard installed on a computer that shipped with Lion is not supported by Apple Support.  It is entirely possible that after a trip for an AppleCare support incident, or the Apple Genius Bar, that the computer will return with Lion installed.


with these caveats, here are the step-by-step instructions:



HowTo - NetRestore - Install Mac OS X 10.6.8 on new Mac delivered with Mac OS X 10.7.0


    note:  this only applies to Macbook Pro, Mac Pro, and iMac computers that originally shipped with Mac OS X 10.6.x. 

               Current Macbook Air and Mac Mini computers cannot be downgraded.


Required resources:

    - another computer, running Mac OS X 10.6.8

    - spare external disk

    - Snow Leopard installation disc  (Mac OS X 10.6.0 or 10.6.3 Box Set)

    - Snow Leopard 10.6.8 Combo image file  (download from Apple Support Downloads page)

    - System Image Utility 10.6.8  (download Mac OS X 10.6.8 Update Combo v1.1.dmg from Apple Support Downloads page)





A. Create the NetImage:

1) mount the base source image  (Mac OS X 10.6.3.dmg - created from Box Set Installer)

2) launch System Image Utility  (from Server Admin Tools)

3) when source (from mounted image) appears in SIU screen, click Custom button

4) drag "Customize Package Selection" from Automator Library window to location

        between existing "Define Image Source" and "Create Image"

5) drag "Add Packages and Post-Install Scripts" from Automator Library to location

        between "Customize Package Selection" and "Create Image"

6) in the "Customize Package Selection" section:

    a) expand the "Mac OS X" triangle

    b) select options desired

    c) collapse the "Mac OS X" triangle

7) mount the appropriate update image  (Mac OS X 10.6.8 v1.1 Combo.dmg)

8) copy the MacOSXUpdCombo10.6.8.pkg package to a new local directory  (Desktop/parts/)

9) drag the MacOSXUpdCombo10.6.8.pkg icon from local directory to the

        "Add Packages and Post-Install Scripts" section of the SIU window

10) in the "Create Image" section:

        a) select the type "NetRestore"

        b) set the "Installed Volume:" field to "Macintosh HD"  (no quotes, can be any name)

        c) select the "Save To:" location

            (will be faster to a second local internal disk)

            (not faster to another partition on the same disk)

        d) set the "Image Name:" field to "Snow Leopard 10.6.8 NetRestore"

        e) the fields "Network Disk:", "Description:", and "Image Index:" don't

            matter unless one is going to use results on a NetBoot Server

11) click the Run button

12) when the dialogs appear, ignore the text and click OK for proper completion

            Dialog text:    "Image creation in progress. 

                            Cancel the image creation to proceed"


B. Post-process to create Restore Image:

1) find the directory created in the above process, named as in A.10d above

            (Snow Leopard 10.6.8 NetRestore.nbi)

2) in this directory are three files:

    - i386

    - NBImageInfo.plist

    - NetInstall.dmg

3) mount the NetInstall image  (double-click the NetInstall.dmg file)

4) navigate into the Contents of the package, to:  System/Installation/Packages/

5) copy the System.dmg file out to desktop or other work location

6) rename System.dmg to meaningful name, such as "Snow Leopard 10.6.8 System.dmg"

7) copy this .dmg file to external, bootable, Snow Leopard 10.6.8 system disk  (install in /Users/Shared/)



C. Install Snow Leopard 10.6.8 on new MacBook Pro or Mac Pro


via command line:

1) boot MacBook Pro or Mac Pro from external source prepared in B.7

2) open Terminal

3) find the restore target device specification

        a) run the command  "diskutil list"

        b) look for a 650 MB partition, labelled "Recovery HD" (likely disk0s3)

        c) the target partition should be immediately prior to the "Recovery HD" partition

        d) for a new computer with a 500 GB drive, this partition should be

                labelled "Macintosh HD", with a size of 499.2 GB

        e) make note of it's Device Identifier, likely disk0s2

4) issue the following asr (Apple Software Restore) command

    sudo asr restore --source "/path/to/restore.dmg" --target /dev/disk0s2 --erase

        (replace "/path/to/restore.dmg" with the path to the location and name used in step b.7)

5) this process proceeds and completes quickly, about 3-5 minutes. This is due to

        the "--erase" parameter; it indicates a block-copy operation

        If the process seems slow, likely the "--erase" option was omitted and

        the copy is being done as a file-copy operation.  Quit (ctl-c) and

        examine the command used...



via DiskUtility GUI:


1) boot MacBook Pro or Mac Pro from external source prepared in B.7

2) launch /Applications/Utilities/

3) select the computer hard drive  (typically "Macintosh HD")

4) click on the "Restore" tab

5) click on the "Image..." button to specify the "Source"

6) navigate to /Users/Shared/ and select the "Snow Leopard 10.6.8 System.dmg" file

7) drag the computer hard drive volume (Macintosh HD) to the "Destination" field

            (note: grab the volume, not the disk!!)

8) enable the "Erase destination" checkbox

9) click the "Restore" button

10) in the ensuing "Are you sure?" dialog, click the "Erase" button

11) authenticate with the local admin credentials



Apple Tech recommends leaving the Restore partition alone, and installing in the "Macintosh HD" partition only


commands to know:

    - asr

    - diskutil      (diskutil -list to see partitions)

    - hdiutil

  • David Armstrong (SE) Level 2 Level 2 (305 points)

    Very helpful Roy.


    Thanks for sharing. 

  • mattalanweiner Calculating status...

    A note about the last part of Step A.  I had to Click OK twice after the nonsense about "Image Creation in Process.  Cancel Image Creation to Proceed."  The first time I clicked OK I didn't see the same message for about an hour.  The second time was about 45 minutes later.  After I clicked it a second time it took another five minutes to complete.  ...I had the feeling it was not going to work.

  • ctrl7 Calculating status...

    Hi Roy.  Thanks for sharing.  Two questions, sorry if I sound like a n00b


    a) is this the absolute easiest way to downgrade/install SL on a single new MBP? (got it today)  or, is it a procedure dseigned for network administrators that take care of multuple computers, or that have to downgrade several units?


    and b)  reading your instructions, it seems that to use Server Admin Tools, one would need to have OS X Server in the first place.... correct?


    Thanks for your help

  • Karina_T Calculating status...

    Hi folks,


    Been faced with a similar dilemma and found this reply online at MacRumours:


    "Or, alternatively if you have another Mac.  Boot the MBP into target disc mode and install 10.6.3 onto it from the other machine.  Then install the 10.6.8 combo update onto it immediately afterwards."


    Does anyone know if this works for sure? I have all the bits to accomplish this but I'm not sure about the upgrade to 10.6.8 as I'm wondering if that would, in any case, have to be performed on the MBP itself...


    In fact I want to go back to 10.6.7 for music and studio management related reasons of my own - i.e, to most closely mirror the setups of a studio of iMacs which I manage.


    Hence I guess I'd do the routine but substitute 10.6.7 for 10.6.8 where appropriate?


    Also, in your case Roy, is the option of going back up to Lion at a later date preservered by following your routine?


    Apologies if my questions sound a bit dim.


    Many thanks.


    Message was edited by: Karina_T

  • Princess Productions Calculating status...

    I tried the "target disk" mode and it did not work.  Applecare replaced my old macbookpro 2008 with an early 2011 - which is awesome except that Pro Tools isn't qualified for it!  It appears to install, but when I go to boot off of that partition, I never get past the apple startup screen, unforunately!






  • Karina_T Level 1 Level 1 (0 points)

    Hi Shari,


    Did you update to 10.6.7 as well? Or wasn't this possible?


    I suspect I'm going to have to go down Roy's route.


    Best of luck.

  • Karina_T Level 1 Level 1 (0 points)



    I went into the Applestore in London and the geniuses were able to find a 10.6.7 Macbook pro install disk (due to a return of a MBP) for my MBP. Started up from the disk and installed fine.


    Only thing is that the F keys no longer map to the things they say on them, e.g., the volume and the mute buttons no longer work, nor the brightness buttons.

    Also the two finger scroll doesn't seem to work so I've a bit of jiggery pokery to do before I'm happy with it.


    But I do seem to have 10.6.7 up and running.


    So maybe pay a visit to an Applestore before too long?


    All the best.

  • Karina_T Level 1 Level 1 (0 points)



    I've done some more tinkering and the problem remains:


    Only F3 and F12  are working the rest give me an error sound when pressed.


    The backlit keyboard works but the trackpad won't do 2 finger scrolling which is a pain.


    I've read many other threads with similar problems going back as far as 2009 but no actual solution.


    I'm expecting a call from an apple genius this afternoon so if I get a fix I'm going to post it here so others can benefit.


    It's very annoying when all I want to do is get on and install software....

  • Karina_T Level 1 Level 1 (0 points)

    Should also add that the dmg I downloaded from apple support - combo updater for 10.6.7 early 2011 MBP



    doesn't want to run on the new mac either...

  • Karina_T Level 1 Level 1 (0 points)

    OK, I found this...



    Where it says:


    "Although these keyboards are designed for and work best using OS X Lion, they also work with Mac OS X v10.6.8 Snow Leopard and iOS—such as with iPad and iPhone. When used with Snow Leopard, the Launchpad key functions as a Dashboard key instead.


    Using these keyboards with operating system software other than Snow Leopard, Lion, or iOS may result in some keys not working as expected; keyboard-based brightness controls, music and video navigation keys, and volume controls may not work as expected. In this situation, control brightness and volume with System Preferences panes. Music and video navigation can be controlled from applications such as iTunes or QuickTime Player."


    ... 10.6.7 may be a problem then?

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