Computing – Introduction to disk partitioning

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Disk partitioning is the generic name given to each division present in a single physical unit of data storage.

A hard disk partition is a logical division in a storage unit (such as a hard drive or flash drive). There are different partitioning schemes for the distribution of partitions on a disk.

The most popular and widespread are MBR (Master Boot Record) and GPT (GUID Partition Table). Partitions to hold data must have a file system. The unallocated space on a disk is not a partition, therefore can not have a file system.

There are multiple file systems with different capacities: as FAT, NTFS, FAT32, EXT2, EXT3, EXT4, Btrfs, FedFS, ReiserFS, Reiser4.

Optical discs (DVD, CD) use other partitions called UDF (Universal Disc Format), which allows you to add files and folders. This is why they are used by most software packet writing and recording programs known as optical drives. This file system is mandatory units for DVD but also allowed for some (CD).

In Windows, the recognized partitions are identified with a letter followed by a two-point sign (eg C : ). virtually all types of magnetic disks and flash drives can be partitioned.

On UNIX and UNIX-like systems, data partitions are mounted on one and the same hierarchical tree, in which they’re mounted through a folder, a process that only the superuser (root) can perform.

However, to be able to use more partitions on a single disk, extended partitions are needed, which can contain an unlimited number of logical partitions within.

It is necessary to note that only the primary and logical partition can contain a file system itself .

Partition Types

The format or file system partitions (eg NTFS ) should not be confused with the partition type (eg, Primary partition), because it actually does not directly have much to do. Regardless of the file system of a partition (FAT , ext3 , NTFS , etc), there are 3 different types of partitions:

- Primary partition: there can be only 4 of these or 3 primary and one extended. It depends on a partition table. A fully formatted physical disk is actually a primary partition spanning the entire disk space and has a file system.

With this type of partition, virtually any operating system can detect and assign a unit as long as the operating system recognizes the format (file system).

-  Extended partition: Also known as secondary partition, it is another type of partition that acts as a primary partition, used to contain multiple logical drives inside. It was designed to break the limitation of 4 primary partitions on a single physical disk.

There can be only one partition per disk of this type, and only serves to contain logical partitions. Therefore, it is the only type of partition does not support file system directly .

-  Logical partition: It occupies a portion of the extended partition or all of it, which has been formatted with a specific type of file system (FAT32, NTFS, ext2) and has been assigned a unit, and the operating system recognizes the logical partitions or file system.

There can be a maximum of 23 logical partitions in an extended partition. Linux imposes a maximum of 15, including 4 primary, SCSI disks and IDE disks 8963.

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