EXTENDED PARTITIONS

When four partitions were no longer enough, a new system was invented. This system consists of creating one or more extended partitions in the four available slots in the MBR. The most common extended partition types are 0x05 and 0x85, with the former used by Windows and Linux and the later used only by Linux. Each extended partition becomes a logical drive with an MBR of its own. Normally only the first two slots in the extended partition MBR are used.

The addresses in partition entries in the extended partition’s MBR are relative to the start of the extended partition (it is its own logical drive after all). Logical partitions in the extended partition can also be extended partitions. In other words, extended partitions can be nested which allows more than eight partitions to be created. In the case of nested extended partitions, the last partition is indicated by an empty entry in the second slot in that extended partition’s MBR. Nested extended partitions are shown in Figure 5.2.

FIGURE 5.2

Nested Extended Partitions.