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GUID Partition Table

aliases:

  • GPT

A hard disk partition style that works by assigning UUIDs to partitions on the hard disk drive and referencing them as needed. Data critical to platform operation is stored in separate partitions, and both primary and backup partition tables are used for redundancy.

GPT partitions can be configured as a basic disk or a dynamic disk. They support a maximum of 128 partitions, depending on the space allocated for the partition table. With GPT, there is no needed for extended and logical partitions.

Data Protection & Recovery

GPT also stores redundant copies of the partition table across the disk, making it recoverable if some of the data gets corrupted. GPT stores CRC values to ensure that the data is intact. MBR doesn't do that, and the end user would only know that something is wrong when the boot process failed or the partitions vanished.

GPT also includes a protective Master-Boot-Record, which sees the entirety of the GPT drive as a single partition that extends across the entire drive. The protective MBR ensures that old tools don't mistake the GPT drive for a non-partitioned drive and overwrite all the data, in case the end user tries to manage a GPT disk with a tool that can only read MBR drives.

Usage Concerns (Raw Lesson Content)

When implementing GPT partitioning, be aware of the following:

  • You should use the GPT partition style whenever possible. However, if you need compatibility with old systems, like the ability to boot Windows off a drive on a computer with a traditional BIOS, you'll need to use MBR.
  • Windows can boot from GPT only on UEFI-based computers running 64-bit versions of Windows 7 or newer, and the corresponding server versions.
    • All versions of Windows 7 and newer can read GPT drives and use them for data, but they cannot boot from them without UEFI.
    • Because Windows 7 does not support UEFI on 32-bit platforms, you cannot boot from a GPT partition on Windows 7.
  • Linux has built-in support for GPT.
  • Apple's Intel Macs no longer use the Apple Partition Table (APT) scheme but use GPT instead.

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