Apple changed the installation process for Lion slightly from earlier versions of OS X. While the process is fundamentally the same, there are differences caused by the new distribution method for Lion, which is sold only through the Mac App Store.
Instead of having physical media (a DVD) to install from, you use the Lion installer app you download from the Mac App Store.
In this step-by-step guide, we're going to look at installing Lion as an upgrade to Snow Leopard, which should be the current working installation of OS X on your Mac.
What You Need to Install Lion
- A copy of the Lion installer. This is available from the Mac App Store. Once you purchase Lion, the installer application is downloaded to your Mac and will appear in the Dock. The installer is actually located in your Applications folder, and is around 4 GB in size. You must have Snow Leopard 10.6.8 installed to purchase and download the Lion installer, however, once the download is complete, you can copy the installer application to any Mac that meets Lion's minimum operating requirements.
- A disk or partition to install the Lion OS on. The Lion installer fully supports internal drives, both conventional and SSD (Solid State Drive) models. The Lion installer also supports external drives, but they must connect to your Mac by USB 2.x, FireWire 400 or 800, or Thunderbolt. eSATA drives aren't likely to work as boot drives; not because Lion won't work with them, but because most add-on eSATA interfaces don't support booting under OS X.
- A minimum of 8 GB of free space to install Lion. You can get by with 8 MB, but practical concerns, such as having enough space to install third-party applications and get a bit of work done, mean that 60 GB of free space is a better minimum threshold.
- A minimum of 650 MB of free space to install the Lion Recovery Partition. When you install Lion, it creates two partitions. The main partition houses the Lion OS and anything else you care to add. The second partition is a small 650 MB partition that contains recovery tools. You can use the Recovery Partition if you ever need to use troubleshooting utilities, such as Disk Utility, on the main boot volume; you can also use the partition to re-install Lion, should the need arise.
With everything ready, let's start the installation process.
