Alternate Boot Disks on x86 Systems

On x86 based systems with a modern BIOS where the boot disk order is properly set, the system boots automatically from the second device if the primary root pool disk is detached, offline, or unavailable. In such systems, you merely need to confirm which active boot device is in the system, as shown in the following example.

$ prtconf -v|sed -n '/bootpath/,/value/p'
name='bootpath' type=string items=1
value='/pci@0,0/pci8086,25f8@4/pci108e,286@0/disk@0,0:a'