Startup Manager: How to select a startup volume

A "startup volume" is a disk or partition of a disk that contains a usable copy of the Mac OS. Startup Manager allows you to choose the startup volume on the fly, by simply holding down the Option key while the computer is starting up.

Capable computers

Startup Manager was introduced with these Apple computers and is present on these and all later models (including all Intel-based Macs):

• iMac (Slot Loading)
• iBook
• PowerBook (FireWire)
• Power Mac G4 (AGP Graphics)
• Power Mac G4 Cube

How to choose the startup volume

Follow these steps:

1. Turn on, or restart, the computer.
2. Immediately hold the Option key. After a few seconds, the Startup Manager should appear. The Startup Manager scans for available volumes.
   
3. Optional: Clicking the circular arrow rescans for other volumes, including NetBoot Server volumes. You can eject any disc in the drive or open an empty tray-loading drive by holding down the Eject key (F12 or key with eject symbol) or, on models that do not have an eject key, holding down Command (Apple) and Period (.) keys. The eject key or Command-Period combination (on models with no eject key) will also close the tray. After inserting a CD capable of starting up your computer, you could rescan for volumes.
4. Click the startup volume you want to use. In the example above, two startup volumes are available: a hard disk, and a CD-ROM disc. The volume's name does not appear.
5. Click the right arrow button to start up the computer from the volume you selected.

Features and Considerations

Displays only one operating system per volume

The Startup Manager only displays one operating system per volume, so how does it choose which to offer you? The Startup Manager offers a volume by the last operating system from which it was started up. From the example above, you may conclude that the hard disk was last used as a Mac OS X startup volume, as indicated by the "X" badge on its icon. For more information, see articles:

106696: "Mac OS: Press X Key During Startup to Select Mac OS X on Single-Partition Installations"
106697: "Startup Manager: Only Displays Mac OS 9, Not Mac OS X
106698: "Startup Manager: Only Displays Mac OS X, Not Mac OS 9"

Each partition with an installed operating system appears

If you have partitioned a hard disk, each partition containing the Mac OS appears with a hard disk icon in the Startup Manager.

Effect is temporary

The Startup Manager temporarily overrides the previously designated startup volume. To save a change, reselect the volume in the Startup Disk pane of System Preferences (Mac OS X) or the Startup Disk control panel (Mac OS 9). Your choice is stored in the computer's parameter RAM (PRAM).

Volume designated in PRAM appears on the left

The previously designated startup volume appears on the left side of the Startup Manager screen. In the picture above, this means that the Mac OS X hard disk was the previously selected startup volume.