Planning an OS X Lion installation involves choosing an installation type to use, as well as preparing your Mac for installation by making backup copies and creating bootable Lion installers.
OS X Lion offers all the usual installation options, including upgrade and clean installation. The difference between Lion and previous versions of OS X is how installations are performed and what you end up with on your Mac when it’s all done.
Recovery volume
A new feature built into any method you use to install OS X Lion is the automatic creation of a recovery partition on the drive. The recovery partition is a small boot volume that contains emergency utilities, such as Disk Utility, and includes the ability to restore from Time Machine and access the Internet. Also on the recovery partition is a copy of the Lion installer, which allows you to reinstall OS X Lion if necessary.
The Lion recovery volume is a nice addition to the operating system, and the ability to boot into this volume and perform maintenance with Disk Utility is a welcome convenience.
However, the recovery partition does not include a copy of OS X Lion. Instead, it connects to Apple’s website and downloads the current version of Lion. Therefore, if you want to reinstall OS X Lion using the recovery volume, you’ll need a reasonably fast Internet connection.
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I mention the recovery volume that Lion creates because it may affect your installation plans. The recovery volume is small, less than 700MB, because it doesn’t include a copy of Lion.
Since you cannot use the recovery volume to install a fresh copy of OS Lion without accessing the Internet, I recommend that you create a bootable copy of the OS X Lion installer so that you can install Lion from scratch at any time, regardless of whether or not you can access the Internet. Creating a bootable copy of the OS X Lion installer is a pretty straightforward process, as you’ll see in the following:
Create a DVD copy of OS X Lion Installer
If you don’t have a DVD burner, you can use the OS X Lion installer to create a bootable flash drive or bootable volume on a drive.
Create a copy of the bootable USB flash drive of the OS X Lion installer
Installation type
Now that we have an emergency bootable version of the OS X Lion installer, it’s time to turn our attention to the type of OS X Lion installation we want to perform.
Updating the Lion installation
The Lion installer is designed for an upgrade installation over an existing copy of Snow Leopard. Updating is by far the easiest process. Once you install Lion, all the data, applications, and other stuff you had in Snow Leopard will be ready for you to install.
The only real downside to an upgrade install is that you lose your Snow Leopard system. If you have any applications that don’t work with Lion, you won’t be able to reboot into Snow Leopard to run them.
There is a way around the problem of lion rewriting Snow Leopard. You can create an additional partition on an internal or external drive, and then clone the Snow Leopard drive to the new partition. This will give you a backup for Snow Leopard, if you ever need it. Even if you’re not concerned about the ability to boot into Snow Leopard, you should make sure you have an up-to-date backup before you start installing Lion.
Instructions for creating a clone of your current startup drive can be found at: Backup your startup disk using Disk Utility
You can also create clones using popular third party applications such as Carbon Copy Cloner or SuperDuper.
Clean Lion Installation
The Lion installer was not designed to perform a clean install, that is, to allow you to erase your current startup drive and install OS X Lion on the erased drive as part of the installation process.
To avoid the lack of a built-in method for performing a clean install, you’ll need an available partition that you can erase before launching the OS X Lion installer. This is a simple process, as long as you have enough disk space, either in the form of multiple drives or a single drive large enough to hold an additional empty partition.
If you don’t have space to spare and you planned to erase your Snow Leopard boot drive, you’ll need to create a bootable copy of the OS X installer, as mentioned above. Once you have a bootable installer for OS X Lion, you can boot from the installer, use your copy of Disk Utility to erase your startup drive, and then install OS X Lion.
What type of installation to use
For new versions of OS X, I prefer to use the clean install option because it ensures a fresh install with no accumulated junk from previous OS versions. The downside is that you have to migrate your data from your previous version of OS X. This extra step takes a bit more time, and you may end up running over the unwanted junk you were trying to avoid by doing the clean install.
However, in my Lion tests, I haven’t found any real issues with using the default update option. I was happy to see that during the installation process, Lion will round up any apps or device drivers that Apple knows have issues with Lion. This decreases the chance of bringing bad juju. That said, I did make sure I had a full backup of Snow Leopard and all my user data by creating a clone on an external hard drive before installing Lion as an update.
If you don’t have an additional drive to back up Snow Leopard, consider purchasing one. External drives are reasonably priced and can be even cheaper if you don’t mind creating your own external drive. You can go back to using the new external drive for Time Machine backups once you’re sure Lion and all your apps and data are compatible.
This is my suggested approach:
- Make sure your version of Snow Leopard is up to date by using Apple’s software update service (Apple menu, Software Update).
- Purchase and download the OS X Lion installer from the Mac App Store.
- Back up your current system using an external drive and a clone process, so that the backup is a bootable copy that you can use in an emergency.
- Create a bootable DVD or USB flash copy of the OS X Lion installer. I recommend the DVD version, if you have a DVD burner. Before you continue, make sure that the USB flash drive or DVD works as a bootable installer.
- Select the type of installation you want to use.
- Use the appropriate step-by-step guide for the type of Lion installation you decide to use.
- Once Lion is installed, take your time and check out its new features. A good place to start is with System Preferences. During the installation process, some of your favorite system settings may have been reset to default. Checking System Preferences will also give you an idea of some of Lion’s new features.