Disk_partitioning

Chapter 12: Disk Partitioning and Tools

Overview

This chapter covers disk partitioning tools and techniques for managing storage in Linux systems.

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12.1 Partitioning Concepts

MBR vs GPT

┌─────────────────────────────────────────────────────────────────────────┐
│                    PARTITION TYPES                                        │
├─────────────────────────────────────────────────────────────────────────┤
│                                                                         │
│   MBR (Master Boot Record):                                            │
│   ┌─────────────────────────────────────────────────────────────────┐ │
│   │ • Max 4 primary partitions (or 3 + 1 extended)                 │ │
│   │ • Max 2TB disk size limit                                       │ │
│   │ • Boot code in first sector (512 bytes)                        │ │
│   │ • Legacy BIOS boot                                              │ │
│   │ • 32-bit LBA for addressing                                   │ │
│   └─────────────────────────────────────────────────────────────────┘ │
│                                                                         │
│   GPT (GUID Partition Table):                                           │
│   ┌─────────────────────────────────────────────────────────────────┐ │
│   │ • Max 128 partitions (default)                                   │ │
│   │ • Max 256TB disk size (theoretical)                          │ │
│   │ • GUID-based unique identifiers                                 │ │
│   │ • UEFI required for boot                                       │ │
│   │ • CRC32 checksums for integrity                                │ │
│   │ • Backup GPT header at end of disk                            │ │
│   └─────────────────────────────────────────────────────────────────┘ │
│                                                                         │
└─────────────────────────────────────────────────────────────────────────┘

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12.2 Partitioning Tools

fdisk (MBR)

# List partitions
sudo fdisk -l
sudo fdisk -l /dev/sdb

# Partition disk
sudo fdisk /dev/sdb

# Commands:
# n - new partition
# p - primary partition
# e - extended partition
# l - list partition types
# t - change partition type
# d - delete partition
# w - write and quit
# q - quit without saving
# p - print partition table

parted (GPT)

# Interactive mode
sudo parted /dev/sdb

# Commands:
# mklabel gpt
# mklabel msdos
# mkpart primary ext4 0% 100%
# mkpart primary xfs 1MiB 100%
# rm 1
# print
# quit

# Scripted
sudo parted -s /dev/sdb mklabel gpt
sudo parted -s /dev/sdb mkpart primary ext4 0% 100%

gdisk (GPT)

# GPT partitioning
sudo gdisk /dev/sdb

# Commands:
# o - create new GPT
# n - new partition
# w - write
# q - quit
# p - print
# i - partition info

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12.3 Partition Examples

Creating Partitions with fdisk

sudo fdisk /dev/sdb

# Example session:
# n (new)
# p (primary)
# 1 (partition number)
# First sector: Enter (default)
# Last sector: +10G
# w (write)

Creating Partitions with parted

# Scripted partitioning
sudo parted -s /dev/sdb mklabel gpt
sudo parted -s /dev/sdb mkpart primary ext4 0% 1GiB
sudo parted -s /dev/sdb mkpart primary ext4 1GiB 100%

Setting Partition Types

# Set partition type (fdisk)
# t command
# 1 - Linux
# 5 - Extended
# 7 - HPFS/NTFS/exFAT
# 8 - Linux LVM
# a - Boot flag

# Set bootable flag
# a command

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12.4 Partprobe

# Notify kernel of partition changes
sudo partprobe /dev/sdb

# Without writing to disk
sudo partprobe -s

# For specific partition
sudo partprobe -s /dev/sdb1

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12.5 Partition Layout

Common Partition Layouts

# BIOS/MBR Layout:
# /dev/sda1  - /boot (512MB-1GB)
# /dev/sda2  - / (root, 20-30GB)
# /dev/sda3  - /home (remaining)
# /dev/sda4  - Extended partition
# /dev/sda5  - swap (2x RAM)

# UEFI/GPT Layout:
# /dev/sda1  - /boot/efi (ESP, 512MB, EF00 type)
# /dev/sda2  - / (root)
# /dev/sda3  - /home
# /dev/sda4  - swap

Arch Linux Installation Example

# Common partition layout:
# /boot     - 512MB to 1GB (EFI System Partition)
# /         - 20-30GB (root)
# /home     - Remaining (user data)
# swap      - 2x RAM (optional with btrfs)

# Example with fdisk:
# n, p, 1, Enter, +512M    # /boot/efi
# n, p, 2, Enter, +30G     # /
# n, p, 3, Enter, Enter    # /home
# t, 1, 1                  # Set ESP type (EF00)

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12.6 Interview Questions

Q: What is the difference between MBR and GPT?
A: MBR: max 4 partitions, 2TB limit, legacy
   GPT: max 128 partitions, 256TB+, UEFI

Q: How do you create a partition in Linux?
A: fdisk /dev/sdb, then n for new partition

Q: What is partprobe?
A: Notifies kernel of partition changes without reboot

Q: What is an extended partition?
A: Container for logical partitions (MBR only)

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Summary

• MBR: Legacy, 4 primary, 2TB limit
• GPT: Modern, 128 partitions, UEFI
• Tools: fdisk, parted, gdisk

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Next Chapter

Chapter 13: LVM - Logical Volume Manager

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Last Updated: February 2026