Creating Partitions with fdisk: Complete Linux Guide

Master Linux disk partitioning with fdisk. Learn partition types, commands, and best practices for effective storage management in this comprehensive guide.

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Creating Partitions with fdisk: Complete Guide

Table of Contents

1. [Introduction](#introduction) 2. [Understanding Partitions](#understanding-partitions) 3. [fdisk Overview](#fdisk-overview) 4. [Prerequisites](#prerequisites) 5. [Basic fdisk Commands](#basic-fdisk-commands) 6. [Partition Creation Process](#partition-creation-process) 7. [Practical Examples](#practical-examples) 8. [Advanced Operations](#advanced-operations) 9. [Best Practices](#best-practices) 10. [Troubleshooting](#troubleshooting)

Introduction

The fdisk command is a fundamental disk partitioning utility in Linux systems that allows users to create, delete, modify, and manage disk partitions. This command-line tool provides direct access to disk partition tables and is essential for system administration tasks involving storage management.

Partitioning is the process of dividing a physical disk into logical sections called partitions, each of which can be treated as a separate storage unit. This allows for better organization of data, installation of multiple operating systems, and improved system performance through strategic data placement.

Understanding Partitions

Partition Types

| Partition Type | Description | Maximum Count | Usage | |----------------|-------------|---------------|--------| | Primary | Main partitions that can contain bootable operating systems | 4 per disk | Operating systems, boot partitions | | Extended | Container partition that can hold multiple logical partitions | 1 per disk | Used to overcome 4-partition limit | | Logical | Partitions created within an extended partition | Unlimited | Data storage, additional file systems |

Partition Table Types

| Type | Description | Maximum Disk Size | Maximum Partitions | Compatibility | |------|-------------|-------------------|-------------------|---------------| | MBR (Master Boot Record) | Traditional partition table format | 2 TB | 4 primary | Legacy BIOS systems | | GPT (GUID Partition Table) | Modern partition table format | 9.4 ZB | 128 partitions | UEFI systems |

fdisk Overview

The fdisk utility operates in two primary modes: - Interactive mode: Provides a command prompt for partition management - Non-interactive mode: Executes specific operations through command-line parameters

Key Features

- Create, delete, and modify partitions - Display partition information - Change partition types - Set bootable flags - Work with both MBR and GPT partition tables - Verify partition table integrity

Prerequisites

Before using fdisk, ensure you have:

1. Root privileges: Most fdisk operations require administrative access 2. Backup important data: Partitioning can result in data loss 3. Identify target disk: Know the device name of the disk to partition 4. Unmount partitions: Unmount any mounted partitions on the target disk

Identifying Disks and Partitions

`bash

List all block devices

lsblk

Display disk information

fdisk -l

Show mounted file systems

df -h

List partition information

cat /proc/partitions `

Basic fdisk Commands

Starting fdisk

`bash

Start fdisk for a specific disk

fdisk /dev/sda

Display help information

fdisk --help

List all disks and partitions

fdisk -l

Work with a specific disk in script mode

fdisk -u /dev/sda `

Interactive Mode Commands

| Command | Description | Usage Example | |---------|-------------|---------------| | p | Print partition table | Shows current partitions | | n | Create new partition | Add primary, extended, or logical partition | | d | Delete partition | Remove existing partition | | t | Change partition type | Modify file system type | | a | Toggle bootable flag | Set partition as bootable | | w | Write changes to disk | Save modifications | | q | Quit without saving | Exit without changes | | m | Display help menu | Show available commands | | l | List known partition types | Display file system codes |

Advanced Commands

| Command | Description | Notes | |---------|-------------|-------| | u | Change display units | Toggle between sectors and cylinders | | x | Enter expert mode | Access advanced functions | | v | Verify partition table | Check for errors | | i | Print information about partition | Detailed partition data | | F | List unpartitioned free space | Show available space |

Partition Creation Process

Step-by-Step Partition Creation

#### 1. Launch fdisk

`bash sudo fdisk /dev/sda `

#### 2. Display Current Partition Table

` Command (m for help): p

Disk /dev/sda: 100 GiB, 107374182400 bytes, 209715200 sectors Disk model: Virtual Disk Units: sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disklabel type: dos Disk identifier: 0x12345678

Device Boot Start End Sectors Size Id Type /dev/sda1 * 2048 2099199 2097152 1G 83 Linux /dev/sda2 2099200 209715199 207616000 99G 8e Linux LVM `

#### 3. Create New Partition

` Command (m for help): n Partition type p primary (2 primary, 0 extended, 2 free) e extended (container for logical drives) Select (default p): p Partition number (3-4, default 3): 3 First sector (2099200-209715199, default 2099200): Last sector, +/-sectors or +/-size{K,M,G,T,P} (2099200-209715199, default 209715199): +10G

Created a new partition 3 of type 'Linux' and of size 10 GiB. `

#### 4. Verify New Partition

` Command (m for help): p

Device Boot Start End Sectors Size Id Type /dev/sda1 * 2048 2099199 2097152 1G 83 Linux /dev/sda2 2099200 4196351 2097152 1G 8e Linux LVM /dev/sda3 4196352 25167871 20971520 10G 83 Linux `

#### 5. Save Changes

` Command (m for help): w The partition table has been altered. Calling ioctl() to re-read partition table. Syncing disks. `

Practical Examples

Example 1: Creating Multiple Partitions on a New Disk

Scenario: Partitioning a new 50GB disk with separate partitions for boot, root, and home directories.

`bash

Start fdisk

sudo fdisk /dev/sdb

Create boot partition (1GB)

Command (m for help): n Select (default p): p Partition number (1-4, default 1): 1 First sector: [Enter for default] Last sector: +1G

Create root partition (20GB)

Command (m for help): n Select (default p): p Partition number (2-4, default 2): 2 First sector: [Enter for default] Last sector: +20G

Create home partition (remaining space)

Command (m for help): n Select (default p): p Partition number (3-4, default 3): 3 First sector: [Enter for default] Last sector: [Enter for default]

Set boot partition as bootable

Command (m for help): a Partition number (1-3, default 3): 1

Write changes

Command (m for help): w `

Example 2: Creating Extended and Logical Partitions

`bash sudo fdisk /dev/sdc

Create primary partition

Command (m for help): n Select (default p): p Partition number: 1 First sector: [Enter] Last sector: +10G

Create extended partition

Command (m for help): n Select (default p): e Partition number: 2 First sector: [Enter] Last sector: [Enter for remaining space]

Create logical partition within extended

Command (m for help): n Select (default p): l First sector: [Enter] Last sector: +5G

Create another logical partition

Command (m for help): n Select (default p): l First sector: [Enter] Last sector: +5G `

Example 3: Changing Partition Types

`bash

Display current partition table

Command (m for help): p

List available partition types

Command (m for help): l

Change partition type

Command (m for help): t Partition number: 2 Hex code (type L to list all codes): 82 # Linux swap

Verify change

Command (m for help): p `

Advanced Operations

Working with GPT Partition Tables

For disks larger than 2TB or systems requiring more than 4 partitions, use GPT:

`bash

Create GPT partition table

sudo fdisk /dev/sdd

Command (m for help): g Created a new GPT disklabel (GUID: xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx). `

Partition Alignment

Modern storage devices require proper partition alignment for optimal performance:

`bash

Check current alignment

sudo fdisk -l /dev/sda

Create aligned partitions (fdisk handles this automatically in recent versions)

Command (m for help): n

Use default values for optimal alignment

`

Script Mode Operations

For automated partition creation:

`bash

Create script file

cat << EOF > partition_script.txt n p 1

+10G n p 2

+20G w EOF

Execute script

sudo fdisk /dev/sde < partition_script.txt `

Partition Type Codes

Common MBR Partition Types

| Code | Type | Description | |------|------|-------------| | 83 | Linux | Standard Linux file system | | 82 | Linux swap | Swap partition | | 8e | Linux LVM | Logical Volume Manager | | 7 | HPFS/NTFS/exFAT | Windows file systems | | b | W95 FAT32 | FAT32 file system | | c | W95 FAT32 (LBA) | FAT32 with LBA | | ef | EFI (FAT-12/16/32) | EFI system partition | | fd | Linux raid autodetect | Software RAID |

GPT Partition Types

| GUID | Type | Description | |------|------|-------------| | 0FC63DAF-8483-4772-8E79-3D69D8477DE4 | Linux filesystem | Standard Linux partition | | 0657FD6D-A4AB-43C4-84E5-0933C84B4F4F | Linux swap | Linux swap partition | | E3C9E316-0B5C-4DB8-817D-F92DF00215AE | Microsoft Reserved | Windows reserved partition | | EBD0A0A2-B9E5-4433-87C0-68B6B72699C7 | Microsoft basic data | Windows data partition |

Best Practices

Planning Partition Layout

1. Boot Partition: Create separate boot partition (100MB-1GB) for complex setups 2. Root Partition: Allocate sufficient space for system files (15-30GB minimum) 3. Home Partition: Separate user data for easier system upgrades 4. Swap Partition: Size according to RAM amount and usage requirements

Size Recommendations

| Partition | Minimum Size | Recommended Size | Notes | |-----------|--------------|------------------|--------| | /boot | 100MB | 500MB-1GB | Kernel and bootloader files | | / (root) | 15GB | 25-50GB | System files and applications | | /home | 5GB | 50GB+ | User data and documents | | swap | 512MB | 1-2x RAM | Virtual memory |

Safety Guidelines

1. Always backup data before partitioning 2. Double-check device names to avoid wrong disk modification 3. Verify partition table before writing changes 4. Test partition layout on virtual machines first 5. Document partition scheme for future reference

Performance Considerations

1. Align partitions to storage device boundaries 2. Place frequently accessed data on faster storage areas 3. Separate I/O intensive partitions across different drives 4. Consider SSD-specific optimizations for solid-state drives

Troubleshooting

Common Issues and Solutions

#### Issue: "Device or resource busy" Error

`bash

Check what's using the device

lsof /dev/sda1 fuser -v /dev/sda1

Unmount the partition

sudo umount /dev/sda1

Stop any processes using the device

sudo fuser -k /dev/sda1 `

#### Issue: Partition Table Corruption

`bash

Backup current partition table

sudo sfdisk -d /dev/sda > partition_backup.txt

Restore partition table

sudo sfdisk /dev/sda < partition_backup.txt

Use testdisk for recovery

sudo testdisk /dev/sda `

#### Issue: Cannot Create More Than 4 Partitions

Solution: Use extended partition to create logical partitions

`bash

Delete one primary partition

Command (m for help): d Partition number: 4

Create extended partition

Command (m for help): n Select (default p): e Partition number: 4

Create logical partitions within extended

Command (m for help): n Select (default p): l `

Verification Commands

`bash

Check partition table integrity

sudo fdisk -l /dev/sda

Verify file system

sudo fsck /dev/sda1

Check partition alignment

sudo fdisk -l -u /dev/sda

Display detailed partition information

sudo parted /dev/sda print `

Recovery Procedures

#### Recovering Deleted Partition Table

`bash

Use testdisk for interactive recovery

sudo testdisk

Use photorec for file recovery

sudo photorec

Restore from backup

sudo dd if=mbr_backup.img of=/dev/sda bs=512 count=1 `

Post-Partitioning Steps

After creating partitions with fdisk, additional steps are required:

1. Create File Systems

`bash

Format ext4 file system

sudo mkfs.ext4 /dev/sda1

Format swap partition

sudo mkswap /dev/sda2

Format FAT32 file system

sudo mkfs.fat -F32 /dev/sda3 `

2. Mount Partitions

`bash

Create mount point

sudo mkdir /mnt/newpartition

Mount partition

sudo mount /dev/sda1 /mnt/newpartition

Add to fstab for permanent mounting

echo "/dev/sda1 /mnt/newpartition ext4 defaults 0 2" | sudo tee -a /etc/fstab `

3. Verify Setup

`bash

Check mounted file systems

df -h

Verify partition table

sudo fdisk -l

Test write access

sudo touch /mnt/newpartition/testfile `

Conclusion

The fdisk utility is an essential tool for disk partition management in Linux systems. Understanding its commands, options, and best practices enables system administrators to effectively organize storage, optimize performance, and maintain system reliability. Always exercise caution when modifying partition tables, maintain backups, and test procedures in safe environments before applying them to production systems.

Proper partition planning and implementation using fdisk provides the foundation for stable, organized, and efficient storage management in Linux environments. Regular practice with these commands and procedures will develop the expertise needed for confident disk management operations.

Tags

  • Disk Management
  • fdisk
  • linux-commands
  • partitioning
  • storage

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Creating Partitions with fdisk: Complete Linux Guide