Types of Partition Table

Partitioning the disks

Created: 2022-07-16
Tags: #fleeting

  • Master Boot Record
  • GUID Partition Table (GPT)
  • partitionless disk

Master Boot Record

  • First 512 bytes of a storage device
  • Contains OS bootloader
  • Storage device's partition table
  • Has an important role of boot process under BIOS system
    Note:
    -> MBR is not located at first partition
    -> It's at first sector of device (physical offset 0), before the first partition

MBR (Bootstrap Code)

-> First 440 bytes of MBR are the bootstrap code area
-> On Bios, usually contains first stage of boot loader
Tip: The bootstrap code can be backed up, restored from backup or erased using dd.
#myquestion What's the use of bootstrap code?

MBR (Partition Table)

-> Other names (DOS or MS-DOS partition table)
Three types of partitions under DOS or MS-DOS partition table

  • Primary
  • Extended
    • Logical

Primary Partition

  • can be bootable
  • limited to 4 partitions per disk
    IF -> MBR partition table requires MORE THAN 4 partitions
    THEN -> 1 Primary partition be replaced by Extended partition with Logical Partion in it

Tip: Dual booting with Windows will require for Windows to reside in a primary partition.

Extended Partitions

  • Can be thought of as containers for Logical partitions
  • Hard Disk MUST NOT have MORE THAN 1 Extended parition
  • Extended partition is also counted as a primary partition
    so IF ->disk has an extended partition,
    THEN -> only three additional primary partitions are possible
    MEANING -> (i.e. three primary partitions and one extended partition)
    WHY -> remember, Primary partition is only limited to 4 partitions per disk
Logical Patterns
  • The number of logical partitions residing in an extended partition is unlimited

Number Scheming when creating Partition

sda1 - sda3 Primary Partition
sda4 Extended Partition
sda5, sda6, ... Logical Parition

Tip:
IF -> partitioning MBR disk
THEN -> consider 33 * 512 byte sector (16.5 KiB) of free unpartitioned spacec at end of disk
WHY -> Just in case you want to convert it to GPT. The space is required for GPT headers

GPT (GUID Partition Table)

Every start of GUID Partition Table

  • ^ used for BIOS/GPT booting with boot loaders that support it.

Partitionless Disk

References

Interactive Graph
Table Of Contents
Types of Partition Table
Master Boot Record
MBR (Bootstrap Code)
MBR (Partition Table)
Primary Partition
Extended Partitions
Logical Patterns
Number Scheming when creating Partition
GPT (GUID Partition Table)
Partitionless Disk
References