Each physical disk drive in a machine is divided into partitions. A partition defines the area of the disk that belongs to a particular operating system. Each disk can be divided into multiple primary partitions and/or one extended partition. Each operating system formats its partition in its own way; this format may or may not be supported by other operating systems.
Only one primary partition on each physical disk drive is accessible at any one time; other primary partitions on that drive are hidden. Boot Manager allows up to four primary partitions on each physical disk drive.
Note that the first physical disk drive in the machine must have a primary partition.
An extended partition can be created in place of one of the four primary partitions when logical drives are desired. All logical drives in an extended partition are accessible at any time, regardless of which primary partition is active, provided that the format of the logical drives is supported by the currently active operating system.