4 (or more) ways to install Mac OS X 10.7 Lion

I’m often wrongly accused of commended on appearing to own an example of every single Mac ever produced. The actual truth is, that, over time, I have accumulated a sizable zoo of Intel-based Macs, all running OS X 10.6 (Snow Leopard). And, with this week’s release of the latest iteration of Mac OS, Lion, I most certainly wanted to upgrade as many of these machines as possible, if only to have the same scrolling direction on all of them.

However, it appears that that’s not always as easy as Apple wants to make us believe. For example, I have a fairly recent 13,3″-MacBook Pro, which should be supported, but refuses all straightforward attempts to upgrade its operating system and just boots into the old one. Also, my (Lion-supported) media-center Mac mini crashed twice halfway into the upgrade process. To make things more complicated, my old 2006 MacBook Pro (featuring a 32-bit-only Core Duo processor) is not officially supported by Lion. In fact, it was only my Mac Pro that was fine with the “just download the Lion Installer through the App store and run it” approach.

In this post I’d like to share a number of different ways to install Lion that I found (mostly on the web) as solutions to very different installation problems.

The regular method

Usually, you just need to follow these steps to upgrade to Lion from Snow Leopard – which is the officially recommended way to get Lion onto your system and worth trying – you might be one of the lucky 99,5%:

Now, as I mentioned, this might not always work. My Mac mini, for instance, failed two times about a third into the installation process; however, after such a crashed installation, the installer will try again after a (forced or soft) reboot – and, alas, on the third attempt it went through. So be persistent.

If this doesn’t work though (or you don’t want to install Snow Leopard before installing Lion), you can try

The DVD or USB stick method

It actually is possible to create more-or-less-regular installation media from the Lion installer, which you can use to boot your Mac (e.g., after you just wrecked your hard drive). For this, you need to extract a disk image called ‘InstallESD.dmg’ from the Lion Installation app’s package (the image is located in the ‘Contents/SharedSupport’ directory – you did make a copy of the installer, right?), and either directly burn it to a DVD (using Disk Utility) or restore it to a 4GB+ USB stick (also using Disk Utility). Detailed instructions can be found here – they should reportedly work (but actually didn’t for me – give them a try, though).

Note that this should work either on an existing Snow Leopard install (I actually didn’t test that), but also allows you to first erase the target disk before installing a fresh and clean copy of Lion onto it (that’s what I finally did). There is, however, another way to do that (which doesn’t need any additional media but involves a FireWire cable):

The target-disk-mode method

My 2010 MacBook plainly refused to boot the Lion installation program – after running the Lion installer, it rebooted straight into the existing Snow Leopard instance. Trying to boot from a Lion installation DVD or USB stick didn’t work, either – though it booted into the installer alright, it didn’t go anywhere from there.

Target Disk Mode to the rescue!

What I finally did was hook up the notebook in target disk mode to another Mac already running Lion (though one with Snow Leopard should work as well). Here, again, it comes in handy if you saved the installer…

You enter target disk mode by holding down the ‘t’ key while (re)starting your Mac. It then effectively behaves like an external FireWire drive, which you then connect (using a FireWire cable) to the other Mac – the target-disk-mode’d Mac’s hard drive(s) should show up as external drives on the desktop.

Then, just run the Lion installer on that Mac and select the boot disk of your target-disk-mode’d Mac as the installation target. Your other Mac will reboot and complete the installation; I recommend to disconnect the FireWire cable after the second reboot and restart your previously-target-disk-mode’d Mac, which will then prompt you to setup the new Lion installation.

Finally, if you are stuck with an Intel-based Mac that isn’t officially supported by Lion (such as a MacBook, MacBook Pro, or Mac mini from 2006/early 2007 originially using a Core Duo or Core Solo CPU) that has been upgraded to a 64-bit CPU, there’s

The unsupported method

Actually, this is similar to the target-disk-mode method (or any other method where you don’t use the actual target Mac for installing Lion – think, for example, of installing to an external disk then used by another Mac). All you need to do is to delete the file ‘/System/Library/CoreServices/PlatformSupport.plist’ within the new installation before booting it on the target Mac. This disables the platform check performed by the operating system on boot. You still need a 64-bit-capable CPU, though – so this apples only to Core Solo / Core Duo Mac minis that have been upgraded by their owners with a Core 2 Duo CPU. My 2006 MacBook Pro is out of luck.

Thanks to Gerd Ohlweiler (and others) for documenting how to do this.

What we don’t know, however, is wether this will reliably work in the long run (e.g., with software updates) – Apple may actually have a reason why these machines are not officially supported…

Recovering a wrecked Lion installation

Once you’ve installed Lion at least once (or actually have one of those new MacBook Airs released alongside Lion), there are other methods to recover from a messed-up installation are described in this Apple support document.

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