Triple Boot Late 2011 MacBook Pro / 10.7 Lion/ 10.6.8 Snow Leopard/ Windows 7
On December 11, 2011 I posted the method I used to make this happen to the apple discussion forums. You may find it helpful:
Yes, you can do all using a USB Drive, see the link in my post above.
I've posted the steps at the discussion linked in my previous post, immediately above your question. Take note that at that link, my original protocol has subsequent addendum post which reduces the total number of steps by adding another. That will make sense when you read it.
I did it booted from SL USB. Mentioned in a couple of earlier posts.
Do need another machine to clone or build the boot SL drive. I have a SL USB drive (actually bare drive with USB/SATA adapter) for testing my troubled MBP 1,1 2006 with X1600 graphic problem. 2011 MBP boots from that no problem. So used Roy's procedure running all on the new machine. 42 mins to build.
1. Clone or build SL on USB drive using another machine that runs SL.
2. Do software update on new Lion machine. (Older Lion Disk Utility is broken.)
3. Use updated Lion Disk Utility to resize Lion partition and make new partition for SL.
4. Boot new machine from USB SL disk.
5. Follow Roy's procedure.
You can use either a USB stick or a USB drive ... doesn't matter other than the ease of use. I find the stick easier. Using the instructional receipe at the Automator link you can build the Snow Leopard NetRestore disk image from a machine booted into either 10.6 or 10.7, per the addendum to my post. Does that clear this up OK?
I talk from Brazil and I would like to ask you one question: In Brazil, there is a version of Mac OS X Snow Leopard 10.6.8 Retail. I have a MacBook Pro 15 Early 20011 with Mac OS X Lion pre-installed. Can I use the Snow Leopard 10.6.8 Retail for make the downgrade on my Mac? If I can, How can I do?
Sorry for my English, because I don`t speak very well.
If there is someone who effectively tested this, so much the better. I remember my experience with trying to install Mac OS X 10.6.0 gm unto an early 2009 white MB—did not work, I needed 10.6.3 for that generation, as you need newer versions for newer generations.
Theoretically, if Lion is preinstalled, it is probable that SL may not work, but there is no absolute rule, if it is a mac generation, which is in between the two OSs you may be do that.
On the other hand, downgrading to SL if Lion was preinstalled has no sense, unless you really need older apps, which require Rosetta or are not simply updated for Lion. Note that Apple will gradually abandon any development for SL so you complicate your life without reason.
You may also consider installing SL unto another partition, if really need be, and if this may work. I once succeeded installing Tiger on the first generation Air’s, using a trick, but this is not an Apple-blessed procedure.
Give a try, I would suggest to put it aside Lion on another partition, if disk size is sufficient. If direct install does not work (you will see a message like ‘the system cannot be installed’ or simply goes into a loop restart), you must use a trick, as long as you have a legal copy of SL: install in unto a mac which supports SL natively, i.e. an older mac; then clone the SL partition unto the new mac unto pre-prepared partition, as suggested. You work best via target mode using firewire cables.
I have not tested thunderbolt connection.
You have to use Lion Disk Utility to repartition the Lion drive. You probably must update Lion first, since there are bugs in early versions of Lion Disk Utility. Once you have done that you can try the install.
Basically, if you can boot from the SL 10.6.8 disk, it will probably work. If you get the three error beeps on boot, it won't. If you look up the causes of the error beeps, Apple documents will say it is bad RAM (no banks), which is not true, just no drivers.
Ian Cheong pointed it correctly. If a direct install does not work (too new hardware), the simplest solution is to have 2 macs, one older (which natively supports SL), one newer (the one with Lion pre-installed). If both have a firewire port, the simplest solution is target mode; you need a fw cable, of course.
If your mac does not have a fw port, than the only solution is to install unto an older mac, and then clone, or directly, if this works. If your mac belongs to the transition generation, you may succeed.
You will not be able to able to boot retail Snow Leopard 10.6.8 to an early 2011 Macbook Pro.
The purpose of this thread was to detail how to downgrade these machines -- which shipped with Lion -- to Snow Leopard. I know it's a lot of pages to go through
Before you try anything, find and download the "Lion Recovery" assistant utility to make a Lion recovery USB stick for the future...that way you can go to Lion later, recover your computer in case of problems, etc. This is important if you decide to wipe out the Lion partition or the hidden Lion recovery partition on your main hard drive.
The favored methods are:
-You can get restore/install discs for the Macbook Pro's from Apple by either calling them or going into an Apple Store and prevailing upon a Genius to help you. If they make you buy the discs, they are 15$. These are special discs with a special version of 10.6.6 or 10.6.7 made for the Macbook Pro's. These discs will boot and can be updated to 10.6.8. Retail discs will not work.
-You can use one of the suggested Target Disc Mode methods if you have a Firewire cable (although you may need Firewire 800 on one end and then a Firewire 400-800 adapter for the other!) and an old Mac that can run 10.6.8. If you can use an old Mac to boot the new Mac's hard drive, retail install, and then you update to 10.6.8 (there were multiple releases of this so get the newest 10.6.8) before attempting to boot the Macbook Pro. Obviously this requires another computer that can run 10.6.8.
-Some people use cloning methods to clone (e.g. using Carbon Copy Cloner) from a Mac running updated 10.6.8 over Firewire to their new Mac's hard drive directly. Or they clone (using CCC) a working 10.6.8 to a USB drive.... which they then restore (using Disk Utility) to their new computer using something like the Lion recovery Disk Utility.
-The purpose of this thread (Roy's "The Procedure" ) was to detail a way to create a pure master 10.6.8 system image which can then be restored (using Disk Utility) to any number of machines.
You can get clever with all of these methods and partition your Lion drive to allow for dual booting or Lion recovery... rather than erasing the Lion drive completely.
These are the general methods that come to mind and many are covered throughout this thread. I wish we could consolidate all the clever ways people have done this.... most of the focus of this thread was using "The Procedure" to create a 10.6.8 master system image but such method may appeal more to geeks and system admins who want to learn to create such images for restore and recovery. For others, simply getting the restore discs for their Macbook Pro (not available for Minis...not sure about iMacs) or asking Apple Store to do it is the easiest route. For those with retail discs, Firewire cables, and an available older Sleo-friendly Mac, Target Disc methods might be the most straightforward.