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Roy Miller Author

Level 1

31 points

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

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)

Procedure:

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/DiskUtility.app

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

Posted on Aug 15, 2011 9:00 AM

364 replies

Aug 29, 2011 7:47 PM in response to Roy Miller

@Roy, FANTASTIC! I was afraid I would not be able to get this running on a non-Apple SSD in my new MBP but lo' your posted method worked a treat. I am thrilled. Thank you so much for your thoroughness! YES!

Aug 29, 2011 11:57 PM in response to Roy Miller

Thanks for the tips Roy. Saved one music producer from the rather awkward situation of not being able to make music on his new mac.

The thought didn't even cross my mind that it would come loaded with lion or that it would be so difficult to revert back to snow leopard.

I ended up getting a little lost at part C and resolved the situation by putting the new mac in target mode and running the install from my old mac. I guess this process would probably negate the need fro an external drive??

thanks again

Roy Miller Author

Level 1

31 points

Aug 30, 2011 7:17 AM in response to dominic01

Hey Dominic,

glad it worked!

I ended up getting a little lost at part C and resolved the situation by putting the new mac in target mode and running the install from my old mac. I guess this process would probably negate the need fro an external drive??

such things as these are always a bit of an adventure. There are several ways to use a variety of disks, thumb drives, or other computers to complete the 'retrograde'. I didn't want to confuse the procedure any more than it may already be by offering a bunch of options - tried to keep it linear and understandable.... 😉

"understandable" - that's a bit of a laugh! However, I suppose the procedure is more understandable once someone has gone through the steps once (or more!?)

you are welcome.

Roy Miller Author

Level 1

31 points

Aug 30, 2011 7:19 AM in response to Wanky

Hi Ed and Tech Harmony,

glad it worked for you!

Ed, dual-boot sounds almost like fun!

cheers!

Sep 1, 2011 10:35 AM in response to Wanky

Hey Guys,

My iMac came with Lion. My music software Logic 8 is no longer compatible, and I don't wanna blow $400 on Logic 9 if I don't have to.

Is it possible for me to partition my drive such that I can keep lion but install snow leopard on a smaller partitioned disk?

Wanky said "I can now dual boot Snow Leopard and Lion on my new MacBook Pro which came with Lion." How did he do this?

I am pretty inexperienced with all this, so if I'm asking stupid questions, forgive my ignorance. 😉

Sep 1, 2011 10:55 AM in response to callofdude16

back up any information you have on lion and go into the disk utility if you click on the hard drive itself not the one that is named Macintosh HD (or whatever you have named it) but the one with more technical looking info on the right half of the window toward the top you will see a bunch of tabs that read "first aid erase Partition RAID Restore" click on the partition one and you want to change it so that there are 2 partitions formatted for mac os x extended (journaled) then once that is done restart and hold the option key during startup this will reveal your hard drive and a recovery drive for lion. insert your OS X SNOW LEOPARD disc and once it is loaded select it. when prompted to select the empty partition without lion that you just named and made. snow leopard will install on that drive and ta-da. to switch back and forth simply hold the option key at startup. use the migration assistant in snow leopard to move files from your back up of lion.

[if you cannot partition the disk while running lion, after you have inserted the os x snow leopard disc and it has booted up you can go into utilities at the top finder bar and open disk utility from there you can partition the drive but it might need to erase everything (thus the need to back up before begining this process) then go through with the install of snow leopard and reinstall lion from backup on the different partitions.]

Sep 1, 2011 11:05 AM in response to Nanotechie1992

oh my gosh, thank you sooo much for the clear instructions. 😀

I'll letcha know if it works :-/

Roy Miller Author

Level 1

31 points

Sep 1, 2011 11:19 AM in response to Nanotechie1992

Much of the info posted by Nanotechie seems reasonable. However, there is a problem with some of it, which has led to this thread and these posts.

insert your OS X SNOW LEOPARD disc and once it is loaded select it.

unfortunately, the current MacBook Pro, Mac Pro, and I'm pretty sure the current iMacs, will not boot on any existing Snow Leopard disk. The only version of Snow Leopard that these current Macs boot in is Mac OS X 10.6.8. Therefore, in the procedure posted at the beginning of this thread, parts A & B are dedicated to creating such a boot volume, while part C is how to install Mac OS X 10.6.8 that was created in parts A & B on your iMac.

Roy Miller Author

Level 1

31 points

Sep 1, 2011 11:34 AM in response to callofdude16

Callofdude - you can follow the instructions for creating 2 partitions on the disk containing your "Macintosh HD" volume, however, then you are still going to have to go through the process, performing all parts A, B, and C, to create a version of Mac OS X 10.6.8 that will boot your new iMac. Then, instead of erasing the whole disk and installing the system, in Part C, Step 3, under the Diskutility GUI method, you should select the new empty partition you created following Nanotechie's instruction.

Prior to doing any of this, you should convince yourself that whatever Snow Leopard disk you have does not successfully boot your iMac. A variety of methods to test this are:

insert you Snow Leopard system installer disk, and do one of the following:

- reboot, and hold down the C key (should then reboot from the optical drive)

- reboot, and hold down the option key. after a while, you should see the bootable disk. If your Snow Leopard install disk appears, after the cursor has turned back into an arrow, click on the Snow Leopard disk, and click the right arrow to continue

- instead of rebooting, after you insert the disk, open System Preferences and select the "Startup Disk" preference pane. in there, select your Snow Leopard disk, and click the "Restart..." button

to really see what is going on with the boot process, and especially to see where/why a boot is hanging, before restarting, open a Terminal window and enter the command:

sudo nvram boot-args="-v"

you'll have to enter your (administrative) password, due to the sudo command. This should be you regular password, if you regular account is the administrative account on the computer.

this will turn on verbose boot and shutdown, and instead of a bland window with a circle of sticks rotating while the computer boots, you'll actually get to see what is being loaded as the system boots up.

to undo this setting, enter the command:

sudo nvram boot-args=""

cheers!

Sep 1, 2011 11:55 AM in response to Roy Miller

Roy's right @callofdude16, you need to test your Snow Leopard install disc before you even proceed with the partition, just to see if it'll even boot from the disc.

I had to contact Apple to get the specific Snow Leopard factory install discs (historically grey but I don't know what they look like yet) that originally came with our Macbook Pro 2011's.

Any retail Snow Leopard disc is just not updated enough to run on these Macbook Pro 2011's. Retail discs have to be 10.6.8 (these don't exist...yet?) whereas the factory install discs have a special version of 10.6.x that can run on our MBP '11's.

If you can't boot from whatever Snow Leopard discs you have, that's your glaring indication that you won't be able to skip Roy's restore method.

Good luck!

Roy Miller Author

Level 1

31 points

Sep 1, 2011 12:02 PM in response to Tech Harmony

Hi Tech Harmony,

did you ever receive model-specific "grey" Snow Leopard install discs for your MBP?

Any retail Snow Leopard disc is just not updated enough to run on these Macbook Pro 2011's. Retail discs have to be 10.6.8 (these don't exist...yet?) whereas the factory install discs have a special version of 10.6.x that can run on our MBP '11's.

my Apple sources tell me there will never be another retail version of Snow Leopard released. Apple is moving onward with software and hardware, as we will all eventually do.

Josh1565

Level 1

0 points

Sep 1, 2011 12:09 PM in response to Roy Miller

Roy,

Great post, we have been researching this for a while, originally contemplating minis and reverting, but this may be a better option with an iMac. I have a couple questions for you:

Do you know if the applecare warranty is Void, or if there is just no suport when installing SL on a Lion iMac?
Have you done any geekbench scores to know if permance has been affected at all? I know with the minis being reverted via target disk mode, that they are suffering some significant performace issues. Likely as disucssed related to Lion hardware not being able to access drivers from SL install.

FOR ALL: Having read the posts on the mini revert and this, it seems that, as Roy says, there many be many paths to the end result, it would interesting to see if anyone has reverted their iMac using the Target disk mode method in it's entirety, posted here, third last post:

https://discussions.apple.com/thread/3209335?start=0&tstart=0

Thanks again Roy for all your help in posting details isntructions, and following up on the postings to provide feedback to us all, it is much appreciated.

Roy Miller Author

Level 1

31 points

Sep 1, 2011 12:35 PM in response to Josh1565

Hey Josh,

my understanding is that currently selling Mac Mini and MacBook Air models now contain hardware for which drivers were never incorporated in any version of Snow Leopard. Therefore, no version of Snow Leopard can fully run these computers, or ever will.

with that statement, it probably depends upon just which hardware was upgraded. For example if is just the wireless network system components that were upgraded, and you don't use wireless, then perhaps a current Mini would run under Snow Leopard, if you could find a way to install it.

Do you know if the applecare warranty is Void, or if there is just no suport when installing SL on a Lion iMac?

I was told that this is "not a supported configuration for these currently shipping Macs" (MBP, MP, iMac). I was told that this would not void my warranty or AppleCare, however if I took one of these in to Apple for service, it could end up being returned with Lion installed, instead of the Snow Leopard system I've installed.

This info was from an Enterprise Apple Technician, who supports our enterprise deployment.

For me, I always clone the hard drive prior to turning a computer in for service. Usually I make two clones, to keep the gremlins at bay! 😉 Therefore, if it came back from service with Lion installed, I'd just revert from my clone....

Have you done any geekbench scores to know if permance has been affected at all? I know with the minis being reverted via target disk mode, that they are suffering some significant performace issues. Likely as disucssed related to Lion hardware not being able to access drivers from SL install.

I haven't. To be clear - I've perfomed this procedure on a MacBook Pro 15", that has since gone to one of my users. I also have a Mac Mini, that I bought specifically to run under Lion, and explore that system. Although I've gone through some hoops to reformat the disk and re-install Lion on the Mini, I've not even tried to retrograde the system to Snow Leopard.

I suspect it is as you say, that the performance issues are due to Snow Leopard not having the correct drivers integrated in the system for the current hardware configuration.

glad this thread has helped at least some folks. It likely won't be too long before new hardware has found its way into MacBook Pro, Mac Pro, and iMac models, and then we'll really have problems retrograding systems.....

cheers!

Sep 1, 2011 3:34 PM in response to Roy Miller

bad news. I "opened System Preferences and selected the "Startup Disk" preference pane. in there, selected my Snow Leopard disk, and clicked the "Restart..." button." And now every time i reboot it can't get past the apple, and this grey screen with a bunch of random text goes over it and it tells me "Restart Your Computer."

AHH?

I can't eject the disk, and I can't do anything.

Help?

Thanks.

Sep 1, 2011 4:01 PM in response to callofdude16

NVM! I FIXED IT 🙂

I held down option while starting up.

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