You just erase your Mac’s drive, install Lion onto it, and then import all your data from your backup. So as long as you have a good backup a 4GB-or-larger thumb drive or external drive and either access to a Mac running Snow Leopard or Lion, or an already downloaded copy of the Lion installer, you can perform a bit of installer razzle-dazzle. It will, however, install onto a blank drive, so Lion clearly doesn’t need any of Snow Leopard’s files or settings.Īs I mentioned above, the Lion installer will let you install Lion onto a bare drive when the installer itself is run under Snow Leopard or Lion.
Based on our testing, the Lion installer refuses to install Lion onto a drive containing Leopard (10.5) in fact, it refuses to install on any drive running a version of Mac OS X below 10.6.6. So then the question becomes whether there are any technical reasons you can’t install Lion over Leopard. In other words, in our view, you should be well within your rights to install Lion on any of your computers for which you have a valid, current Snow Leopard license-even if you don’t install Snow Leopard on it first. While the letter of the law says you need to install Snow Leopard before installing Lion, the spirit of the law seems to be that a particular Mac just needs a license for Snow Leopard before you can install Lion on it.
Having performed this two-step upgrade many times while researching our various Lion-installation articles, I can tell you that it’s a real hassle.)īut lets take a step back. (This is just one scenario-I can think of a number of situations in which you might have Leopard on a Mac or an external hard drive, along with a valid license for Snow Leopard, and you’d rather not take the interim step of installing Snow Leopard just to upgrade to Lion. But what if, for example, you’ve got a family-pack license for Snow Leopard, and you’ve got a Mac that shipped with Leopard but that you never upgraded to Snow Leopard? Assuming that Mac is compatible, the Lion license agreement says you can’t upgrade to Lion until you first install Snow Leopard. Disadvantages: requires an internet connection and new enough firmware since everything is coming over the internet, booting will be slower than with your own recovery drive (and again, reinstalling Lion will require 4GB worth of patience).Those situations are pretty clear.
Advantages: doesn't require any advance preparation as above, you can boot from this and recover from Time Machine and/or reinstall Lion (if you have enough time).
Disadvantages: you must create this before removing the old HD, it requires an 1GB or larger flash drive, and since it won't include the full Lion installer you'll need an internet connection (and 4GB worth of patience) to reinstall Lion with it. Advantages: you can boot from this and recover from Time Machine (and/or reinstall Lion if you have an internet connection and enough time). Create a Lion Recovery drive (per my answer above) using an existing Lion system and Apple's Lion Recovery Disk Assistant.Disadvantages: you need to download the installer first (around 4GB), and it requires an 8GB or larger flash drive. Advantages: just like the purchased installer, you can boot from this and reinstall Lion and/or recover from Time Machine without needing an internet connection. Create your own Lion installer drive (per Diago's answer) using a downloaded Lion installer app.Advantages: you can boot from this and reinstall Lion and/or recover from Time Machine without needing an internet connection. Buy a Lion installer (USB drive) from Apple.There are a number of similar options that can be a little confusing, so here's an attempt at clarifying their differences: Then, after you replace the HD, you can boot from that and use it to reinstall Lion and/or recover your system from Time Machine. I'll add yet another option to the list: before you remove the old HD, use the Lion Recovery Disk Assistant to copy its recovery partition to a flash drive.