Mac OS X 10.4, 10.5 installation options:

When you're ready to install Mac OS X 10.4, 10.5 or later, you may notice that you have several installation options available to you while started from the Install disc. If you prefer not to custom install, simply install the software using the default installation.

If you'd like to see your choices, click the Options button that appears when choosing an installation destination. A dialog sheet appears and presents you with several installation choices, listed below. Here's what each type of installation provides.

Upgrade to Mac OS X, Install Mac OS X:

The Installer will present one of the above choices to you, depending on which volume you've selected for installation. If a previous version of Mac OS X is on the selected volume, "Upgrade to Mac OS X" appears (unless the installed version can't be upgraded, as described in this article). If no version of Mac OS X is installed on the volume, "Install Mac OS X" appears.

About Upgrade to Mac OS X:

Upgrading to Mac OS X takes a little longer than installing it on a volume without Mac OS X, but it is the least intrusive way to install--most of your existing settings and applications are left untouched during an upgrade. In other words, you won't have to configure a lot of settings afterwards.

If you're having issues with your currently-installed version of Mac OS X, upgrading may not resolve those issues. Instead, you might benefit more from doing an Archive and Install installation (see "Archive and Install," below).

If you're reinstalling Mac OS X 10.4 or 10.5 on a volume that already contains the same version, you will see Upgrade to Mac OS X as the first choice.

About Install Mac OS X:

Install Mac OS X appears when the installer finds a destination that does not already have Mac OS X installed (or it appears that way). If parts of Mac OS X are missing, this option may appear instead of Upgrade to Mac OS X.
If the selected volume can't be upgraded or software can't be installed on it as is, this choice will be dimmed (unavailable). For example, you can't choose to upgrade or install Mac OS X 10.4 client on a Mac OS X Server 10.3 volume.

Note: If you've updated Mac OS X 10.4 or 10.5 to a later version than what is on your Install disc, you can't use this option, but you can use others described below.

Archive and Install:

Select this option if you want to install a "fresh" system on your computer. This type of installation moves existing System files to a folder named Previous System, then installs a new copy of Mac OS X. You cannot start up your computer using the Previous System folder.

Archive and Install installations require the largest amount of available disk space because you need to have room to preserve your existing System and the new one you are installing. This is a good choice if you've already backed up your important files and are trying to resolve an existing issue. Mac OS X-installed applications, such as Address Book and Safari, are archived, and new versions are installed in the Applications folder. For a list of which files are archived, see this article.

Some applications, plug-ins, and other software may have to be reinstalled after an “Archive and Install.” Fonts that were installed in the Fonts folder in the top-level Library folder can be installed in your new system by copying them from the Previous System folder.

About "Preserve Users and Network Settings":

You'll probably want to select the "Preserve Users and Network Settings" checkbox to import your existing accounts' Home folders, and network settings into the new system. Home folders include things such as:

Files on your desktop and in the Documents folder

Your personalized preference settings

Address Book contacts and databases

Favorite locations and Web browser bookmarks

iTunes songs and iPhoto pictures

Your network settings and locations

"Preserve Users and Network Settings" also copies the existing Shared folder in the Users folder to your new system.

Third-party software:

Important: Usually it's best to reinstall third-party software after an Archive and Install installation to ensure they work correctly. The "Preserve Users and Network Settings" option leaves non-Apple-installed (third-party) items intact, though they may be moved, depending on their location.

After installation:

You might wonder "What do I do with the Previous System folder?" It may contain items that you need. To determine this, once you've finished configuring, installing, and updating your applications, you can compare the Previous System to the new System. If there are things in the Previous System folder that aren't in the new System folder, copy them over or reinstall. If you're not sure what some items are (and don't seem to need them), leave them in the Previous System folder. Once you're comfortable that you've got everything you need out of it, you can delete the Previous System folder (or leave it around if you have enough free disk space).

You can’t start up your computer using the Previous System folder, but settings, preference files, fonts, plug-ins, and other items remain available in case you need to access them (which you probably won't, if you use "Preserve Users and Network Settings").

Erase and Install:

This option completely erases the destination volume, then installs a new copy of Mac OS X. You should always back up important files on the target volume before using this type of installation.

This is the fastest way to install Mac OS X, but it may take some time to set up your computer after installation. You will have to configure all of your computer settings, install your third-party and iLife applications, and restore your personal files from the backup you made.

Why use this option?

If you've already backed up your computer, this might be a good choice if you are trying to resolve an existing issue and an Archive and Install installation didn't help.
This option takes up the least amount of space when the installation is completed.
This is a good option if you no longer need the information on the computer, and you have another computer that you would like to easily transfer stuff from ("migrate").
Volume format choices
Once you've selected this option, you can choose from two types of volume formats:

Mac OS Extended (Journaled)—This is the default option and should be used unless you have a specific reason not to.

UNIX File System—Only choose this option if you specifically need it.
Does an Erase and Install change partition configurations?
No, it uses the current settings. It also doesn't configure advanced RAID settings or perform a secure erase. If you want to do any of these things, use Disk Utility before installing; you can access Disk Utility while started from the Install disc.

Troubleshooting Mac OS X installation from CD or DVD:

For a successful upgrade or installation of Mac OS X, the installer will need to complete all of the following steps:

  • Start up from the Install or Restore disc (all Mac OS X versions)
  • Computer check (Mac OS X 10.4 or later)
  • Source disc check (checks your installation DVD or CD, Mac OS X 10.4 or later)
  • Destination (hard drive) check (checks the installation volume, Mac OS X 10.4 or later)
  • Install Mac OS X (all Mac OS X versions)

If you have issues with the above steps, or have any of the following questions, use the troubleshooting tips in this document.

  • Unable to start up from the installation disc?
  • Cannot complete computer check?
  • Cannot complete source disc check (checking your installation DVD or CD)?
  • Unable complete destination (hard drive) check (checking Installation Volume)?
  • Install starts but does not complete (an alert message appears)?
  • Issues after the installation finished?
  • Is it OK for reinstallation to be slower?

Starting up from the disc:

Usually, you can start from the disc by putting it in your computer, restarting, and holding the C key. Or, put it in the computer and click the Install or Restore icon you see in the disc's main window (after which the computer will start from the disc without you needing to hold C.)

Mac OS X 10.4 tip: If your computer ejects the Mac OS X 10.4 Tiger Install DVD, your Mac probably doesn't have an Apple internal DVD drive or Apple SuperDrive, in which case you'll need Mac OS X 10.4 Install CDs. (If it does have an Apple DVD-ROM drive yet still ejects the disc, see this document.) If you need Mac OS X 10.4 Install CDs, check out the Mac OS X Upgrade website.

Troubleshooting tip: If the computer doesn't start from the disc—you never see the option to choose a language, for example—then see this document for troubleshooting tips.

Computer check:

The Mac OS X Installer makes sure your computer can use the version of Mac OS X you're trying to install.

Troubleshooting tip: If you see a message that you cannot install Mac OS X on this computer, even though it should work with Mac OS X, you may need to install a firmware update. Restart your computer from the hard drive and install the latest firmware available for your computer.

Source disc check:

During this helpful step, Installer takes a few moments to check the source disc itself before starting the installation process. If you see a message about a "failed checksum," then there may be an issue with your optical disc or optical drive (see the tips below).

Note: During this step, you may see a "Skip" button in the Installer window. If you haven't used your Install disc before (or recently), you should not skip this step.

Troubleshooting tips:

1. Is that disc clean? Make sure the disc is clean and without significant smudges or deep scratches. If your disc is unusable, call AppleCare support for assistance.

2. Is this this original optical drive? If you have issues, make sure you're using the original Apple optical drive that was included with your computer (CD-ROM, DVD-ROM, DVD-RAM, CD-RW, Combo drive or Super Drive). This is only a concern in three scenarios: if you have replaced your original Apple drive with a non-Apple drive, if you have added a non-Apple drive to the second bay of a Power Mac G4 model with two drive bays, or if you are attempting to install from an external drive.

3. Will the disc's data copy to hard disk? If your computer will start up from any existing version of Mac OS, try copying the contents of the installation disc to your hard disk (if you have enough space). The ability to copy (but not install) the data is a simple test of the disc and of the hardware. If you encounter repeated errors, the hard disk or the disc may be unusable.

4. Can you isolate the issue to a single computer? If you have access to a computer with a spare hard disk or partition that can be erased, then you may test the installation disc on it to verify that the disc is good. After the test is complete, the test disk or partition should be erased if you are only licensed to install the software on one computer.

Destination disk check:

Before the actual installation begins, the installer checks the selected volume to ensure the integrity of the disk. If the disk check finds issues that it cannot repair, the installation will not start.

You must resolve such hard disk issues before you can install. If you have a third-party disk utility that's compatible with your version of Mac OS X, you can try that. If no utility can correct the issue, you must back up your important files, then perform an erase install.

Mac OS X 10.4 Tiger tip: See Only use Mac OS X 10.4-compatible disk utilities with Mac OS X 10.4 volumes.

Tip: You can also contact an Authorized Apple Service Provider (AASP) for assistance.

Installation starts but does not complete?

f you intentionally skipped the "Checking your installation DVD or CD" (Source disc check mentioned above) step at the beginning of the installation, you should allow the check to complete to make sure the installation media is OK.

If you see a message such as one of these, use the tips below:

"There were problems installing the software"

"There were errors during the installation...Please try again."

"Because of a problem, installing Mac OS X could not be completed."

"Installer could not validate contents of the [PackageName] package" (where '[PackageName]' is the name of one of the packages on the installation disc).

Tip: RAM issues may cause an installation issue such as this. Try removing any third-party RAM that's been installed. Remember to make sure you have at least 128 MB (Mac OS X 10.3 or earlier), 256 MB (Mac OS X 10.4), or 512 MB (Mac OS X 10.5 Leopard or later) of memory installed.

You can also retry the installation on the same computer, or try a different compatible computer (as a test) to determine whether the issue is isolated to the Mac OS X disc or to the computer itself.

Did the installation finish?

If the installation of Mac OS X finishes and the computer restarts, it is highly unlikely that anything is wrong with your disc or that Mac OS X was "installed incorrectly." If you have issues that aren't related to installation, this document can help.

It's OK if reinstallation is slower:

Installing Mac OS X on a disk that already has Mac OS X is slower than installing on a disk that has no Mac OS X installed. That's OK because of the file comparison that happens during a reinstall takes a little time. See the note on "downgrade" installations here.

Additional Information:

Mac OS X: Troubleshooting installation and software updates