Extended Partition Definition

An extended partition is a primary partition that has been divided up into logical partitions as a means of creating more partitions than the four that would otherwise be possible.

A partition is a logically independent section of a hard disk drive (HDD). A primary partition is any of the four possible first-level into which a HDD on an IBM-compatible personal computer can be divided. Logical partitions are partitions that are created by dividing up the extended partition.

Only one primary partition can be used as an extended partition, and it can be created from any of the primary partitions. The logical partitions do not need to fill the entire extended partition.

The sizes of the logical partitions are described at the beginning of the extended partition, not in the master boot record (MBR). The MBR is is a small program that is executed when a computer begins to boot up (i.e., start up) in order to find the operating system and load parts of it into memory.

Created April 9, 2006.
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