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

Okay team, I put everybody's efforts on a website here:

https://sites.google.com/site/downgradeyourmac/

"The Procedure" is here

https://sites.google.com/site/downgradeyourmac/the-procedure

There are links to screenshots and I put up the Target Disc Mode method as well.

It was epic. I tried to proof everything and nail down some confusion/ambiguity but I'm sure I introduced more 😉 Still, it's all here and should be a good guide for whatever route you want to take.

Extra Notes: I tidied/edited/combined @Roy's "Procedure," his updated wiki entry; @Josh1565's work and great screenshots; @zirkenz's various tips, discoveries, and Target Disk Mode method; with a nod to @OliverW's prompt-skip trick. In other words, it's a lot of information lol.

I know it's not easy for others to update the pages or anything but let me know if there are things you think I should fix. If it gets serious, then I can add collaborators 😉

I think the sections about which hard drive partitions, volumes, target discs to use in Disk Utility are probably the most ... intense ... because it seems to me like it would be easy to choose the wrong "Macintosh HD" ... so I tried to put in a little more detail on how to do this. Let me know how it goes!

And always back up any data that's important to you before you start mucking about with systems. The more you know! *ding*

Confirmed: New iMac 2011 that shipped with Lion now running Snow Leopard at full speed. Found and borrowed a 10.6.7 original issue install DVD to install on separate partition from Lion. (This is the grey disc that Apple included in 2011 model prior to release of Lion. The companion Applications Install disc has iLife along with the traditional bootable Apple Hardware Test which runs fine on the machine.)

Several previous methods all got it running smoothly under 10.6.8, but always at half-speed: (a) cloning boot drive of MBP, (b) cloning boot drive of iMac 2010, (c) install from 10.6 retail disc followed by 10.6.8 combo update.

In the end, there appeared to be no hardware of firmware differences with models shipped in May and June -- and there do appear to be machine-specific elements on the original DVD that were not available otherwise. Running at half-speed was not an acceptable option. The machine would otherwise have gone back to Apple.

Would be interesting to know the technical reasons for the speed difference.

Tech Harmony wrote:

ds store wrote:

Can someone please summarize the results, limitations, models and methods to reverting a new Lion factory Mac to Snow Leopard?

• Macbook Pro 2011: yes can downgrade to Snow Leo, no speed compromises on my i5
• Mac Pro 2011: sounds like it's running fine
• Mini 2011: there's another thread about it but it sounds like those folks are only able to install and run Snow Leo at half-speed.
• iMac 2011: recent model sounds like it's running at half-speed on Snow Leo
• Macbook Air: don't know; people may tell you it's impossible

[....]

3. You can see if there are Snow Leo restore discs for your model computer from before it got rolled over into Lion. You can order/cajole these from Apple. These discs existed for any model that was out before Lion was out... so like the MBP 2011 but not the MacBook Air. There's an Apple link in the ether which details which computers came with which restore discs.

[....]

There is an easier way that does not entail a complete reinstall of the OS. You can use BootCamp to install Snow Leopard and keep Lion as well. All you have to do is adjust the partition size to whatever you want. If you want Snow Leopard as your main OS just increase the size of the partition to however much you think you need. This will also allow you to delete the partition when (and if) Lion becomes more stable without have to do a reinstall. I went the other way and installed Lion on a BootCamp partition on my 24" iMac, which turned out to be a wise move. However, I have Lion running on my MacBook Air and can happily say, I have no real issues with it other than older software not being supported.

SR

hi. first of all, thanks a lot for the turorial created by tech harmony (and to the people that put their brains on it). i know nothing about the process but with the tutorial (step by step and with the images) it was really easy for me to get to the begining of the step c. then i read about the firewire cable that i need to complete the downgrade (targe mode)... so, there is a way to do the part c whitout a firewire cable? like from a external drive or something.

sorry if its a dumb question but i dont know much about it... and i only want to make music and lion still useless for that...

saludos

Oy, I should put a warning about the Firewire cable in the required resources! The other way is if you have an external hard drive I think!

Hmmm, if you have an external hard drive or thumb drive, you might be able to "restore" the 10.6.8 System.dmg from the host to the external hard/thumb drive first.

THEN drag a copy of the 10.6.8 System.dmg somewhere onto the external/thumb drive as well for easy use later.

Then if you plug this external drive into your target Lion Mac and boot it up while holding down the "option" button, maybe you can select your external drive as the boot drive?

If you can boot from the external/thumb drive then you can use its Disk Utility to try to now restore the 10.6.8 System.dmg you dragged onto your external drive, to your Lion Mac volume.

I don't know if the original NetInstall procedure is to help you install all this over the network ..... I don't know how to put the Lion Mac into a network mode that can be reformatted and downgraded to Lion!

thanks for the tip but it didnt work. i just simply put a copy of the system.dmg into my external disk and then connect it to the mbp and hold the option key while i turn it up but i only see the macintosh hd volume and the recovery volume. it did not boot from my external disk...

That won't do it. You need to do something like:

1. Open Disk Utility and find your external disk drive in the list on the left .Click on it. (For each drive you see the disk identification information (sizeGB, model, brand) and then their normal name(s) below the identifier, indented, these are the volumes)
2. The "Restore" tab-button will appear above the right area. Click on it.
3. "Source" click the "Image..." button and select your 10.6.8 System.dmg from your desktop.
4. "Destination" drag the external volumefrom the external drive's information into the Destination area... .make sure you grab the correct volume! THIS WILL ERASE THE VOLUME SELECTED. Click the box that says "Erase destination" (it will only erase the volume selected).
5. Click the "Restore" button and it will proceed to put make a bootable external 10.6.8 drive
6. When it completes, drag the System.dmg file to the drive as well...you can make a folder called "IMAGES" and put it in there but that doesn't matter.
7. Properly eject the external drive and plug it into your Lion Mac
8. Reboot your Lion Mac while holding down "option" key around when you hear the chime
9. You should now be able to select the external drive''s Snow Leopard 10.6.8.
10. Once it boots up, you will probably have to run through setup... that's fine.... as soon as you can, run Disk Utility.
11. Resume "The Procedure" at 2.3.1.4 [but basically your "Source" will be the 10.6.8 System.dmg you dragged onto your external drive and "Destination" is now your Lion Mac volume that you are erasing and ovewriting...You've already done the step where you backed up your Lion Recovery disk... dual booting requires repartitioning which is sort of touched upon in step 4 here.

I didnt get it the first time i read the "restore" instruction in your first reply, but with your last reply i carefully follow the steps and i only have to say: THANKS A LOT. Now i have my MBP running with SL and i made a backup too for the lion system in a external drive... nice. So thanks, and if some day for some reason you are in mexico let me know to invite you some nice tequila and mezcal...

Saludos

Wooooooooohoooooooooooooooooo!

These reports of systems running at half speed seem very suspicious. That sounds like some artificial limitation.

There is very little in Lion that is a real advantage over Snow Leopard: Lion did make some improvements but nothing that should double the speed of a system.

Would be interesting for someone to use some low level debugging to see what is actually going on and perhaps get it fixed. Maybe the Darwin projects could take a peek.

Hi all,

I have followed the tip of others and got myself a 10.6.7 disc specific to my new iMac from applecare. Installed, and it brought up to ful speed, but I do not notice any change in operating speed, so likely it is a superficial thing.

Anyways, jsut figured I would post for others, getting a disc is possible, and installing OVER my 10.6.8 netinstall worked fine.

Good luck all.

Josh

Good work everyone!

I'm going to go over all the "methods" as I currently have severe brainfry, am directing those who need to go back to Snow on a factory Lion Mac to this thread.

this is awesome, guys. noticed before reading about the topic (yesterday)...things like "You cannot install this version of mac OS x because you're using a later version"...."Do not use any earlier version of Mac OSX on your new mac".

...what gives? you can put windows xp on a new computer...you could choose not to upgrade from leopard or snow leopard on a mac...you can install an old linux on pc/mac....what about complex Mac applications....they're not written (or optimized) for lion....forced upgrading?