Prerequisites

Globally Unique Identifier (GUID) is a 128-bit number used to identify information in computer systems. In other contexts, they are also known as Universally Unique Identifiers (UUID). Their purpose is to be unique across all space and time, making it extremely unlikely that the same identifier will be generated by anyone else.

GUIDs are used in software development for various purposes, such as identifying software components, ensuring uniqueness in database keys, and more.

GUIDs are typically represented as a string of hexadecimal digits, divided into five groups, such as 3F2504E0-4F89-11D3-9A0C-0305E82C3301. This format ensures a high probability of uniqueness due to its vast range of possible values.

Definition

Standard layout of partition table on a physical storage device used in a desktop or server PC, such as hard disk drive or solid-state drive, using GUIDs.

GPT is part of the Unified Extensible Firmware Interface (UEFI) standard, a replacement for the older Master Boot Record (MBR) partitioning scheme used by BIOS systems.

GPT's design and capabilities make it the preferred choice for modern computing environments, offering greater flexibility, reliability, and support for future hardware advancements.

Key Features

1. Increased Partition Limit - Unlike MBR which is limited to 4, GPT allows for a theoretically unlimited partitions (typically capped at 128)
2. Larger Disk Support - Supports disks up to 9.4 ZB (Zettabytes), whereas MBR is limited to 2 TB due to its use of 32-bit fields for storing sector addresses. This makes GPT more suitable for modern large-capacity drives.
3. Improved Data Integrity - Includes cyclic redundancy checks (CRC) values to check integrity of its data. This can help detect errors that might corrupt the partition table.
4. Backup Partition Tables - Stores both primary and backup partition tables, one at the beginning and one at the end of the disk as a redundancy in case of corruption.
5. Compatibility - A protective MBR is located in the first sector of the GPT disk for legacy software compatibility. But it does not contain valid partition information like traditional MBR does.