While Apple's Mac OS X installer does a good job at handling migration from one version of the OS to another, or at least the Tiger edition worked well for most Mac users, still, migration is a critical time for your data and settings files, so it's best to be prepared and plan for the worst.
There was some good discussion on a Leopard migration thread on Apple's OS X Server mailing list. Mac IT manager Dan Shoop offered a number of warnings to Tiger and Panther Server sys admins.
The reasons OS X admins have so much trouble with updates and upgrades is that as a group they have such little understanding of how they have their systems configured. Other OSes force better practices and systems hygiene. Larger shops document their systems and configurations better.
And Apple released its Leopard Server Migration Guide the other day.
Of course, Leopard Server is a much different animal than the client platform. But it's good to consider migration advice for the Mac OS X 10.5 Leopard client (Techmeme review roundup) . Here's some things to consider now before you run out on Friday evening, buy a copy of Leopard and then upgrade your system:
1. Make sure you have a clone of your entire working system on an external hard drive. If something goes wrong, you can simply force your Mac to boot from the external drive. (Note: This is done by holding down the "N" key at boot-time, which starts the Mac into the Startup Manager. There you can select a Mac OS X volume to start from.) If your Mac is working well enough to go into System Preferences, you can choose the older external drive in the Startup Disk prefs.)
In the IT department, there are two recovery variables: the Recovery Point Objective, which is the age of the data you will be able to restore your records to after you have a failure; and Recovery Time Objective, which is the time you will need to resume your business activity after a discovering a problem.
A clone of your current working drive with all its data files and applications should give you a handle on both the point and time objectives. However, the longer you go before uncovering a problem, then the age of your data for the recovery point may become an issue. So, it's important to really pound on the new OS and your software applications right after it's installed. Don't just ooh and ah over the new eye candy.
2. Make sure you examine all the applications and plug-ins that you run in your mission-critical workflow. What are the applications that you need to do your work and do you know now that they will work under Leopard? If not, perhaps you should wait on the upgrade and check for updates in the next couple of weeks.
As I mentioned in an earlier post, some HBA cards may have trouble with Leopard. So, you have to look at your entire workflow, software and hardware. 3. Record all your online identities and passwords. Many Mac users (and Windows users too) don't remember their user names and passwords for logins. They just rely on the Keychain authentication management utility to remember them. And many users don't record identities and passwords in a file or in hardcopy (or they do the other wrong thing and put them on a Post-it next to their machine.) This is very important info.
What if the keychain breaks or becomes corrupted? Can you find out who you are? Maybe not. Your Keychain information is very important. You should make a remote copy, perhaps to .Mac or some other remote service.
4. Make sure that you have important settings recorded, such as your server logins. I am always amazed to find that many users rely entirely on bookmarks to connect to Web-based management interfaces for routers and aliases for server volumes. Or they don't know the correct user name/password combinations for managing and connecting to WiFi routers.
If something happens to those settings, they will have no clue how to connect to the server or to the router. Perhaps the person with that information is away and can't be reached.
I admit that this happened to me a while ago with an old wireless router in the closet. I had to download the user manual and perform a hard reset on the hardware, which wiped out all the MAC addresses for all the devices I own. It was a big pain.
5. Do you have the licenses for your applications? These settings can also be trashed, causing your software to stop working or shift into demo mode. You may have to reinstall your applications (worst case) or just reenter the registration numbers. If you don't have the license numbers handy, you won't be able to use the apps.