Leopard’s release is mere hours away here in the United States. Is your Mac ready for Apple’s next big cat? Here are some steps you can take to get your Mac up and running with Leopard.

Before you upgrade

Decide if you should upgrade right away

If you are on a PowerPC Mac and rely on Classic apps for whatever reason, do not upgrade to Leopard. Leopard does not support the Classic environment.

If you rely on your Mac for your business (e.g. you are a freelance designer and require Creative Suite to work flawlessly), you may want to hold off on installing Leopard until the third-party vendors you rely on can ensure that their products will work with Leopard. Additionally, some users choose to hold off on upgrading until the initial release bugs are fixed. The choice is yours.

Disable system hacks

If you are not planing a clean install, remove or disable any system-wide hacks. This includes haxies, Input managers, and other hacks you may have applied to the operating system. Note that as of now, Unsanity has not confirmed that their haxies will work with Leopard. Some haxies and other system hacks may cause conflicts with Leopard. After you upgrade, install Leopard-compatible versions.

UPDATE: Rosyna from Unsanity tells me that APE 2.0.3 simply disables itself when you are running Leopard, so older haxies should not cause any problems. In fact, Unsanity does not recommend uninstalling APE, since other 3rd-party apps may require APE’s presence even if it doesn’t do anything. If you are using a version of APE earlier than 2.0.3, upgrade to 2.0.3 before upgrading to Leopard (earlier versions can cause complications), and watch this page for compatibility updates.

UPDATE 2: Slava from Unsanity has posted a blog entry addressing this issue.

Watch your free disk space

Leopard takes up a good deal more disk space than Tiger (about 9 GB for a full install of Leopard vs. about 3 GB for Tiger). If you’re tight on disk space as it is, clean out what you can before installing Leopard. Copy files you don’t need onto an external hard drive or burn them to a CD or DVD.

A good rule of thumb is to keep at least 10% of your hard drive free at all times, otherwise you may experience slowdowns. If you still don’t have sufficient disk space, you may need to upgrade to a larger hard drive before upgrading to Leopard.

Install software updates

I am going to echo what Macworld suggested in their fine article, Getting your Mac ready for OS X 10.5. Fire up Software Update and make sure all your Apple software is up to date. Hit up VersionTracker and download the latest versions of all your apps. Some apps have built-in update-checkers as well. Note that not all applications are Leopard-ready yet. We are keeping track of Leopard-ready software updates for a number of software developers, and we will continuously update the list as we find out more.

Check your drive

And here’s another Macworld suggestion I too am going to suggest doing: give your hard disk a once-over with Disk Utility. Typically the OS install CDs have a copy of Disk Utility bundled with it. You’ll want to use that version as opposed to the version installed on your Tiger hard drive because that one can only verify the disk. If you don’t have Leopard and aren’t afraid of entering text commands at a DOS-like prompt, do the following:

1. Restart your Mac while pressing Command-S. This will boot your Mac into Single-user Mode.
2. When prompted, type “fsck -f” and press return. OS X will scan the disk. Lather, rinse, and repeat until OS X tells you that no problems were found.
3. When you are done, type “exit” and press return. Your Mac will continue booting.

If Disk Utility or fsck fail, you will probably need a third-party utility like DiskWarrior.

Back it up. Back it up real good!

It’s a good idea to keep a copy of your last known working setup, just in case something goes horribly wrong. I suggest performing an operation known as “cloning” your drive. A hard drive clone is a bit-for-bit copy of the original drive. If anything goes wrong, it will be easy to restore your Mac with a cloned drive.

My weapons of choice are Bombich Software’s Carbon Copy Cloner and a LaCie Porsche external Firewire hard drive. I prefer Firewire because it allows me to boot my Mac off the backup drive and clone the backup back onto the original drive, no matter which Mac--my iBook or MacBook--I use. PowerPC Macs can’t boot off of USB drives, while Intel Macs can. Additionally, you can use it for a really cool trick, which I’ll mention a little later.

In fact, I’ll probably continue using Carbon Copy Cloner over Time Machine for one big reason: you can not boot off of Time Machine backups.

While installing Leopard

Upgrade, Archive and Install, or Clean Install?

There are three options for installing Leopard: “Upgrade,” “Archive and Install,” and “Clean Install.”

An Upgrade basically overwrites whatever system files have been updated and leaves everything else--like kernel extensions or hacks you may have installed--intact. Up through Tiger, this is the default for upgrading a Mac. I have yet to install Leopard, so I can’t say for certain if the Upgrade option is still the default, but I’d be surprised if Apple changed it.

Archive and Install will move your old Mac OS X system (and the old versions of bundled apps) to a folder named “previous system,” and gives you a pristine new System folder and applications. This is my preferred method since I want a ‘cleaner” install than an Upgrade, but am too lazy to go through a Clean Install. You will likely need to sort through the “Previous system” folder and salvage files you still need, though.

A Clean Install is as its name suggests: it wipes your entire hard drive clean and installs a brand new system onto it. Some prefer this method because it allows them to start with a clean slate and reduce the possibility of conflicts.

Be selective

If you don’t need all the printer drivers or foreign language support included in the default installation, don’t install them. At some point in the installation, a “Customize” button should appear, allowing you to pick and choose what you want to install.

Now for that cool trick I mentioned earlier...

Did you know that you can use a clone of your previous Mac OS X setup on an external Firewire drive, you can restore the files using Mac OS X’s Migration Assistant? No kidding! When the Migration Assistant asks you to attach a Firewire cable between your old Mac and new Mac, plug in your external hard drive. When the Migration Assistant tells you to turn on your old Mac and hold down the “T” key, switch on your external drive.

This same sort of thing might be possible with Time Machine in Leopard, but we have yet to test it.

After you upgrade

Make sure everything works

First off, test your applications--especially mission-critical ones--and make sure that they play nice with Leopard. If they don’t, well, you’ll be very glad that you made that backup before upgrading. For non-critical apps, notify the developer of the problems you are having, and keep watching for Leopard-ready updates.

If you find bugs, report them

If you find any bugs in Leopard, report them to Apple. You can use their Mac OS X feedback page, or if you are an Apple Developer Connection(ADC) member, you can submit it via Apple’s developer bug report form. If you are not an ADC member, become one. An online membership account is free.

If you do report a bug, be specific. When does it happen? How? Can it be reproduced?

Have fun!

Need I say more?

Previous Days of Leopard articles

Days of Leopard is Deep Thought’s series of Leopard-related articles posted in the days leading up to and immediately following Leopard’s launch on October 26, 2007. Collect them all!

• Deck your Mac out Leopard-style
• Is Leopard really a major upgrade?
• Mac developers gear up for Leopard
• Musings on the Finder