If you eject (unmount) any partition on a disk, all partitions from the same disk are also ejected, except for a partition that contains the startup System Folder. File Sharing and Classic are also affected.
Note: Apple does not ship Mac OS X installed on partitioned hard disks. This document applies to systems using hard disks that have been intentionally reformatted and partitioned.
Tip: Ejecting a volume may not mean that it is physically ejected from the computer, but that it is no longer available (mounted) on the desktop or in a Finder window.
Tip: With Mac OS X 10.3 and 10.4, you can eject a single partition or volume, if you wish, by using Disk Utility. You cannot eject a partition via the Finder in Mac OS X 10.4.
Symptom
1. Effect on a startup disk:
When three or more partitions are on the startup disk, ejecting one partition causes all other partitions, except the startup partition, to also be ejected.
2. Effect on a non-startup disk:
Ejecting one partition on the disk causes all partitions to be ejected. Removable media are physically ejected.
3. Effect on File Sharing:
Sharing from the startup partition via AppleShare (AFP) becomes unavailable, but FTP remains available.
4. Effect on Classic:
If you eject the partition that contains Mac OS 9 and then try to start up Classic, you an alert box with this message appears:
"To start Classic, you need Mac OS 9.1 or later installed. See your documentation for instructions on installing this software."
Note: The volume containing the designated Classic System Folder (Mac OS 9) also counts as a startup partition. If Mac OS X and Mac OS 9 are installed on separate partitions and Classic is running, then neither of the two partitions would be ejected.
"To start Classic, you need Mac OS 9.1 or later installed. See your documentation for instructions on installing this software."
Solution
Check before you eject
Before you eject a partition, be sure that any files contained on it are no longer in use. Look at the Dock to see what applications are active.
To make a partition available again
For removable media, reinsert the media.
1. To use a hard disks partition, restart the computer to make all partitions available, or use Disk Utility instead. Follow these steps to use Disk Utility:
2. Open Disk Utility (/Applications/Utilities/).
3. Click the disclosure triangle to the left of the hard drive icon to display the names of your hard disk volumes and partitions.
4. Select any dimmed partition name in the Disk Utility window. It is not necessary to select more than one dimmed partition name.
5. Choose Mount from the Options menu. All non-mounted partitions on the selected hard disk appear on the desktop again.
6. Quit Disk Utility.