Upgrading your Mac’s operating system is a bit like removing your house’s existing foundation to add a new garage underneath. In both cases, the procedure is conceptually simple: set aside the parts you want to keep; remove some old pieces; add some new pieces; replace the original structure onto the new foundation; and reconnect all the infrastructure that was severed in the process. Assuming all goes well, the final product is more stable and has wonderful new features.
In the case of Mac OS X 10.4 Tiger, tens of thousands of pieces—the files that make up the operating system and your data—must go into just the right places with just the right settings. Ensuring that this happens is the job of the installer application, which knows what needs to go where. Apple wants you to think of the process as a simple one: double-click the installer, answer a few easy questions, wait for the installation to complete, and enjoy your new operating system. And to its credit, Apple has made some wonderful improvements in the Tiger installer that promise to eliminate many frustrations of earlier upgrades. Many users will have just the sort of trouble-free upgrade we all hope for.
Even so, a major system upgrade such as this one is a complex operation with many potential pitfalls. Problems can and do occur. Some users will find that they can’t complete the installation process but won’t know why: Some will be unsure which options to choose, or what effect they’ll have. Some will be unable to reboot their Macs after the installer finishes. Some will be unable to print or access the Internet. Some will lose important data, encounter software incompatibilities, or find that their peripherals no longer work. I’ve run into all these problems and more at one time or another, and I want to spare you such inconveniences.
An important note before we begin: As with any major system upgrade, make sure you have a current backup before proceeding. Take Control of Upgrading to Tiger contains additional advice on preparing for the upgrade and solving problems you may encounter.
Choose an Upgrade Method
For users with an earlier version of Mac OS X already installed, the Tiger installer offers three upgrade options:
You will select one of these methods later, when you run the installer, but you should know about them now, because the method you choose will determine some of the other preparatory steps you must take. Most users will opt for the default choice, assuming that Installer Knows Best. In an ideal world, this would be the most painless upgrade. Unfortunately, with every new system upgrade, some users who choose this method run into serious problems—especially if they don’t prepare for it properly.
(If you install Tiger onto a volume that does not already have a Mac OS X installation, the Upgrade Mac OS X choice becomes Install Mac OS X. This option installs a clean copy of Tiger on the selected volume, but does not erase any other files that may already be present there.)
In Take Control of Upgrading to Panther , I recommended Archive and Install (with some modifications) for most users. With Tiger, however, Apple has added a new file transfer capability that makes Erase and Install a more attractive option for many users—while also presenting you with an array of potentially confusing options. Ultimately, your choice of upgrade method will depend on your Mac setup.