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You guys are making it hard. This is the definitive way to make a bootable clean OS X install.

1. You need an External HD or USB flash drive. At least 8GB. This method doesn't work with DVDs.

2. Open Disk Utility and find your HD/USB drive. On the partition tab, click options and ensure GUID Partiton Table is selected. If it isn't, you will need to format the entire drive to change it.

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Make sure You Partition is formatted Mac OS Extended (Journaled) aka HFS+.

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3. If your Lion is from the Mac App Store, find Install Mac OS X (probably in Applications), right click and go to Show Package Contents. Go to Contents/Shared Support and copy InstallESD.dmg to somewhere like the desktop or another folder. If you have you Lion from a torrent/rapidshare etc. you probably have InstallESD.dmg

4.You now need to see the hidden files. To do that, open up Terminal and paste the following

Code:
defaults write com.apple.finder AppleShowAllFiles -bool true
killall Finder


4. Mount InstallESD.dmg and you should see a file that was previously hidden called BaseSystem.dmg. Mount it.

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5. Back in Disk Utility, find the volume created in step 2 (mine was called Lion Install) and hit the restore tab. The source should be BaseSystem.dmg and the destination should be your volume (again, mine was Lion Install). Click restore and enter password if autenticate if prompted.

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6. You should now have a USB (or Firewire if you using it) called "Mac OS X Base System". Rename it and change the icon if you want. I renamed mine back to Lion Install and gave it the Lion icon.

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7. Copy the "mach_kernel" file from the InstallESD.dmg file to the root your USB installation.

8. Back to InstallESD.dmg, copy the "Packages" folder and paste it on USB Lion installation in /System/Installation. Replace the "Packages" alias that is already there.

File Structure should look like this. Ensure mach_kernel are in the root of the volume and the Packages folder is in the /System/Installtion folder.

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You can now turn off hidden files. Again, paste the following in Terminal

Code:
defaults write com.apple.finder AppleShowAllFiles -bool false
killall Finder

Reboot your Mac, hold the option key and you should get something like this.

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Boot it up and you should see a screen very familiar to past Mac OS X installations. Access to things like Disk Utility, Firmware password etc. are all there.

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I'm not quite sure why all of you are so obsessed with a clean install. Is all the fuss really worth it? I upgraded SL to Lion GM and I have no problems, no slow downs, no crashing... NADA!

So relax, let the Lion installer do its thing, enjoy your coffee and come back to your computer in 20 minutes. Done.
 
I'm not quite sure why all of you are so obsessed with a clean install. Is all the fuss really worth it? I upgraded SL to Lion GM and I have no problems, no slow downs, no crashing... NADA!

So relax, let the Lion installer do its thing, enjoy your coffee and come back to your computer in 20 minutes. Done.

I have a question, I am going to update to Lion from Snow Leopard when it comes out. Now say 6 months later I want to restore my macbook pro and start from scratch, do I need to install SL which the macbook pro came with and then install Lion or will it automatically install Lion for me since it was on my mac right before I needed to restore it.
 
I'm not quite sure why all of you are so obsessed with a clean install. Is all the fuss really worth it?

You're being short-sighted...

Some aren't quite ready to literally wipe out all remnants of snow leopard just yet. They want to install the Lion GM to another clean partition just to get some hands on first.

I will keep flipping back and forth between OS's before I make up my mind whether to "officially" upgrade.
 
You're being short-sighted...

Some aren't quite ready to literally wipe out all remnants of snow leopard just yet. They want to install the Lion GM to another clean partition just to get some hands on first.

I will keep flipping back and forth between OS's before I make up my mind whether to "officially" upgrade.

Then do exactly that. It is possible to create a partition with disk utility and then run the Lion installer from your SL partition. During the installation process it asks you which partition you would like to install Lion on.

I guess I should have been more specific in my original post. I was referring to all of the Terminal commands people are doing and formatting hard drives just to get a "clean" install of Lion... seems a little over the top.
 
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I have a question, I am going to update to Lion from Snow Leopard when it comes out. Now say 6 months later I want to restore my macbook pro and start from scratch, do I need to install SL which the macbook pro came with and then install Lion or will it automatically install Lion for me since it was on my mac right before I needed to restore it.

Boot from the Lion recovery patition (Recovery HD) and select Reinstall Mac OS X. Now the issue I have with Apple doing this is that it redownloads OS X every time you do this which is so unnecessary. I have download caps on my Internet, I cant give up 4GB everytime I need to install Lion. What if you have 3-4 Macs in the house? Thats 16GB you need to download Lion on every machine.

Regardless of whether you wants to clean install or not, you should make yourself a DVD or USB installer.
 
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I have a question, I am going to update to Lion from Snow Leopard when it comes out. Now say 6 months later I want to restore my macbook pro and start from scratch, do I need to install SL which the macbook pro came with and then install Lion or will it automatically install Lion for me since it was on my mac right before I needed to restore it.

This is something I'm not quite sure any of us can answer at this time. It is a first for Apple to distribute an OS by only digital means. Your question should be answered in a support document when Lion is released, I'm assuming.

EDIT: Forgot about the Recovery HD, as mentioned above. Shouldn't have to install SL before Lion.
 
You can d a clean instal 6 months down the track from the recovery partition. Only downside i see it needs to re-download.
 
To those saying Lion requires SL to be installed, I'm pretty sure that's not the case. I opted for a clean install as well on my MBP. The disk only has one partition, so I booted my MBP from a SL backup on an external drive, and launched the installer from there, right after using disk utility to wipe the MBPs internal drive. I could have just as well used a USB stick or DVD.
 
To those saying Lion requires SL to be installed, I'm pretty sure that's not the case. I opted for a clean install as well on my MBP. The disk only has one partition, so I booted my MBP from a SL backup on an external drive, and launched the installer from there, right after using disk utility to wipe the MBPs internal drive. I could have just as well used a USB stick or DVD.

Is this basically the same functionality as the recovery partition that Lion makes? I'm at work so I can't test this, but for instance, could you install Lion normally within SL, boot into the recovery partition, erase "Macintosh HD/your boot drive that is now OS X Lion", and then "Restore OS" and have it download Lion again?

Sounds like a hassle, but I don't think Apple would intend the typical user to extract a hidden file to restore to an external drive and copy some files into this and that in order to do a clean install of Mac OS X.
 
Is this basically the same functionality as the recovery partition that Lion makes? I'm at work so I can't test this, but for instance, could you install Lion normally within SL, boot into the recovery partition, erase "Macintosh HD/your boot drive that is now OS X Lion", and then "Restore OS" and have it download Lion again?

Sounds like a hassle, but I don't think Apple would intend the typical user to extract a hidden file to restore to an external drive and copy some files into this and that in order to do a clean install of Mac OS X.

I suppose Apple is confident enough in their improved OS-upgrade process that they feel it unnecessary to offer an alternative. Either way, it's not impossible and googling "Lion bootable disc" gives you 20 different sites that outline the procedure.

BTW, in your example I think it would be a lot easier to use a truly separate partition (like in my case, a different drive) or a form of bootable media. That way you don't have to re-download anything, and you only install once.
 
These writeups on creating bootable DVDs and flash drives seem much easier than much of what's been posted so far. Going into the Terminal? Really? I used these steps to make my bootable install drives with no issues. Still a shame Apple isn't including a bootable flash drive or DVD option for those that want a clean install without a 2nd partition taking up space on your drive (something some SSD users can't afford).

http://subrosasoft.com/blog/2011/07/create-a-bootable-mac-os-x-10-7-lion-flash-drive/

http://subrosasoft.com/blog/2011/07/create-a-bootable-mac-os-x-10-7-lion-dvd/
 
Boot from the Lion recovery patition (Recovery HD) and select Reinstall Mac OS X. Now the issue I have with Apple doing this is that it redownloads OS X every time you do this which is so unnecessary. I have download caps on my Internet, I cant give up 4GB everytime I need to install Lion. What if you have 3-4 Macs in the house? Thats 16GB you need to download Lion on every machine.

Regardless of whether you wants to clean install or not, you should make yourself a DVD or USB installer.

how do I access the recover partition exactly.
 
I did a clean install of Lion GM without problems from a USB Flash Drive (8GB)

All I did was located the InstallESD.dmg file, and dragged that into my diskutil app as the source, and then selected my USB Flash Drive as the volume for my destination and let it copy over, and then rebooted by holding OPTION key down and selected the USB Flash Drive to boot into the Lion GM Install.

I didn't have to do any of that base install.dmg copying or whatever.
 
All I did was located the InstallESD.dmg file, and dragged that into my diskutil app as the source, and then selected my USB Flash Drive as the volume for my destination and let it copy over, and then rebooted by holding OPTION key down and selected the USB Flash Drive to boot into the Lion GM Install.

That's exactly what I did, but I get the gray circle with a slash in it whenever I attempt to boot from the USB drive.
 
Can Lion be installed to a blank drive (as in brand new) from the dmg on a USB.

I tried with DP1 and it errored out after loading into the installer. It needed Snow Leopard present somewhere on the drive, im guessing to take some files from it.

If it can install to a blank drive ill be a happy man.
 
Can Lion be installed to a blank drive (as in brand new) from the dmg on a USB.

I tried with DP1 and it errored out after loading into the installer. It needed Snow Leopard present somewhere on the drive, im guessing to take some files from it.

If it can install to a blank drive ill be a happy man.

I just installed it to a blank partition fine. Lion GM that is.
 
I did a clean install of Lion GM without problems from a USB Flash Drive (8GB)

All I did was located the InstallESD.dmg file, and dragged that into my diskutil app as the source, and then selected my USB Flash Drive as the volume for my destination and let it copy over, and then rebooted by holding OPTION key down and selected the USB Flash Drive to boot into the Lion GM Install.

I didn't have to do any of that base install.dmg copying or whatever.

That sounds great (much simpler) but using this method do you get the disk utility and other system maintenance options that you get on say a retail snow leopard dvd, and of course the lion recovery partition. Just curious if this was the reason why the previous poster added all the other steps.
 
I didn't know that you could simply restore InstallESD to a USB volume. When I first installed Lion, I installed it on my hackintosh first, then my MacBook Pro. That method that I posted works for both whereas simply restoring InstallESD to USB doesn't work on a hackintosh.

If there's one thing though, my method

1. Goes through the install process faster because it doesn't restart
2. Doesn't create the (what I feel is unnecesssary) Recovery HD partition.
 
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