Disk Partition

A disk partition is a defined region of a physical drive that behaves like a separate disk. Each partition can hold its own file system, such as NTFS, ext4 or APFS, and is recorded in a partition table, either MBR or GPT.

Why it matters

Partitions let you keep the operating system apart from personal data, install several operating systems on one drive or reserve space for recovery tools and swap. Reinstalling the system on its own partition leaves the data partition untouched. GPT is the modern table format and supports drives larger than 2 TB, while MBR is limited to 2 TB and four primary partitions.

Example

A 1 TB drive on a Linux machine might look like this:

/dev/sda1   512 MB   EFI System
/dev/sda2   100 GB   ext4   mounted at /
/dev/sda3   899 GB   ext4   mounted at /home

Windows shows partitions as drive letters, such as C: and D:, in Disk Management.

Common mistakes

• Resizing or deleting partitions without a backup; a power cut mid-operation can corrupt data.
• Confusing a partition with a separate physical drive. Two partitions on one disk fail together.
• Deleting the small EFI or recovery partitions, which can make the system unbootable.

Related

• Disk formatting
• File system
• BIOS and UEFI
• Dual boot

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