Power PC-based Macs: Unable to start up from a FireWire drive that contains multiple hard drives

Some PowerPC-based Macs may not be able to start up from an external FireWire drive that contains multiple hard drives. The drive may be selectable in Startup Disk, but attempts to boot to them are not successful or the drive does not appear Startup Manager (hold down the 'option' key on startup).

  • These drives tend to have a larger capacity (1 to 2 terabytes); they accommodate larger storage sizes by using multiple hard drives grouped together in a hardware-based Redundant Array of Independent Disks (RAID).
  • These drives usually come bundled with a software utility that allows you to configure them as RAID 0 (Striped) or 1 (Mirror) volumes. When configured, they appear as a single hard drive in the Finder and in Disk Utility.
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These drives can be used as startup volumes, but they will only be bootable if the Logical Unit Number (LUN) is zero.  

To determine the LUN of the external FireWire drive, perform the following steps:

  1. Go to /Applications/Utilities and double-click Disk Utility to open it.
  2. Select the hard drive to highlight it as shown below.
  3. Choose Get Info from the File menu.
  4. Locate the Device Tree text field then locate the number after that follows "/@" as shown below.
    If this number is zero, the device should be bootable.
  5. If the LUN is not zero, there are probably other devices connected to the FireWire bus and one of them already has a LUN of zero.
    1. If the software utility that was bundled with the drive allows you to assign a LUN, use it to change the LUN of the drive you wish to use to zero and change the other devices to a non-zero number.
    2. If your software utility does not offer LUN assignment (many of them do not), disconnect the other devices from the FireWire bus so that the drive you want to use is the only device on the FireWire bus.
Important: Information about products not manufactured by Apple is provided for information purposes only and does not constitute Apple’s recommendation or endorsement. Please contact the vendor for additional information.
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