Jaguar Upgrade: What Gets Archived

This is the third in a series of posts I’m writing about my upgrade to Mac OS X 10.2 “Jaguar”.

As described in the previous post, I chose the Archive & Install method of upgrading. This moves a variety of installed system software into an archival location in the /Previous Systems directory. Understanding exactly what gets moved, and some quirks of the archive itself, are useful when you begin your post-installation configuration work.

Here’s what gets archived into /Previous Systems/Previous System X/:

• Applications/
  This folder archives all of the applications Apple supplies as part of the base Mac OS X install. This does not include the iApps, like iMove, iTunes, and iDVD, and it does not include any of the third-party applications you’ve installed yourself.
  • Utilities/
    Same story here, all of the Apple-supplied base utilities get archived.
• bin/ [invisible]
  /bin contains most of the system’s default command line tools on BSD Unix. From what I can tell, the entire contents of the /bin directory get archived. I didn’t install any new command line tools here (the correct place for user-installed command line tools under BSD Unix is usually /usr/local/bin), so it’s possible user-installed tools would be left in place.
• Developer/
  This will only be archived if you installed Apple’s Developer Tools. The old tools are incompatible with Jaguar, so they are completely archived. You must install the new versions of the Developer Tools to restore access.
• etc/
  This is a symlink (think alias) to /private/etc, also archived. Details below.
• Library/
  This is your former /Library directory, and it’s where most of the important things for normal users will be archived to, and many items will need to be restored. (I’ll cover restoration in the next post.)
• mach
  This is a symlink to the mach.sym file (below). It’s essentially junk, you would never normally need to re-use this.
• mach_kernel
  A semi-critical system file, also never likely to be re-used.
• mach.sym
  A semi-critical system file, also never likely to be re-used.
• private/
  This is a critical directory for people who have mucked about with the Unix layer of Mac OS X. The two most important directories are:
  • etc/
    This directory contains many configuration files for Unix applications, including Apache and ssh, configuration files that determine which servers and services will be launched on startup, periodic tasks and maintenance, and the like.
  • var/
    This directory contains many important logs and messages, including mail if you’ve enabled sendmail, as well as some system configuration files used by NetInfo, among many other things.
• sbin/ [invisible]
  This is another collection of command line Unix tools. These are considered “critical”, as may of these tools are used in the event of system recovery. From what I can tell, all of the tools installed by Mac OS X in /sbin get archived here.
• System/
  This is the core operating system directory, of which the dominate item is the Library/ sub-directory. This is where all the core system files, such as CoreServices, Classic, various Frameworks, the Java stuff, and a variety of critical OS X system elements are stored. Since this directory is supposed to be off-limits during normal use, there should be little that you’ll need to re-use here. If you have installed kernel extensions (such as drivers for the Griffen iPort, or your SCSI card, etc.), you’ll probably need to re-install them. However, you should definitely check with your vendor to ensure they’re Jaguar-compatible. Nothing will make your Mac OS X system unstable like an incompatible kernel extension.
• Users/Shared/
  All of your individual Users directories are preserved and saved in the upgraded system, except for the Shared directory, which is archived. This is something you might want to put back into your /Users directory, especially if you’ve put stuff there. Myself, the only thing I found was some AOL Instant Messenger resources, and since I’ve switched to iChat in Jaguar, I have no need for AIM.
• usr/ [invisible]
  This is a critical Unix directory, and is where you would install most extra Unix tools and applications, if you’ve been installing applications like MySQL or PostgreSQL. There’s also a slew of “secondary” command line tools installed by Mac OS X. And some of your favorite GUI applications may put command line tools that augment their functionality here (BBEdit is one of these).
• var/
  This is a symlink to the private/var/ directory, described above.

That’s everything that gets archived. Note that three directories, those marked with an [invisible] above, are normally invisible when in use by the system, and are archived invisible also. This makes it hard to get to them, when you’re ready to start doing your post-installation configuration work. It’s highly useful to use a tool like XRay to uncheck the Invisible bit on these archived directories, so you’ll have no difficulty getting to them later.

Tomorrows post: Post-Installation Reconfiguration.