A hard disk drive can be divided in to several storage units. These storage units are called partitions. Creating partitions would make a single physical disk drive appear as multiple disks. Software that can be used to create, delete and modify partitions is called a partition editor. Creating partitions would allow the user files to be resided separately from the operating system and other program files. Furthermore, partitions would allow the user to have multiple operating systems to be installed in different partitions of the same hard disk. Initially, a hard disk drive could be divided in to two partitions called the primary partition and extended partition. The extended partition could be further divided in to multiple logical drives. Information about the partitions in a computer is included in the Partition table, which is located in the Master Boot Record (MBR).
| Primary
Partition |
Logical Partition 1 | Logical Partition 2 | Logical Partition 3 | Logical Partition 4 |
↑
Extended Partition
What is Primary Partition?
A disk drive can contain a maximum of four primary partitions or three primary partitions and a single extended partition. One file system is contained in a primary partition. Unlike earlier versions of Microsoft Windows systems, more recent Windows operating systems such as Windows XP, Windows 7 could be placed on any partition. But the boot files should be located in a primary partition. Partition type code of a primary partition indicates information about the file system contained in the primary partition or the whether the partition has a special usage. When there are multiple primary partitions in a hard disk, only a single partition can be active at any given time and the other partitions will be hidden. If a drive needs to be bootable, it needs to be a primary partition.
What is Logical Partition?
The extended partition in a hard disk drive could be subdivided in to several partitions called logical partitions. The extended partition acts as a container for logical partitions. The structure of the logical portions in the extended partition is described using one or more Extended Boot Records (EBR). EBRs that describe multiple logical drives are organized as a linked list. Each EBR comes before the logical drive described by it. The first EBR will contain the starting point of the EBR that describes the next logical drive. After the logical partitions are formatted using a suitable file system they will become visible.
What is the difference between Primary Partition and Logical Partition?
Primary partition is a bootable partition and it contains the operating system/s of the computer, while logical partition is a partition that is not bootable. Multiple logical partitions allow storing data in an organized manner. Multiple primary partitions in a hard disk drive are described using a single partition table that is contained in the MBR, while multiple logical drives in hard disk are described using multiple EBRs. Due to this reason the number of primary partitions that could be created in a hard disk is limited (maximum is four), whereas the number of logical drives that could be created is limited only by the available hard disk space. Generally, primary partitions are assigned the first letters in the alphabet as drive letters (such as C, D) whereas logical drives get the other letters (such as E, F, G).