Creating Partitions and Filesystems - fdisk and mkfs

2026-05-30 Reading time: About 14 min Difficulty: Intermediate

What You Will Achieve

• Explain the difference between MBR and GPT and how to choose
• Create partitions with fdisk / gdisk / parted
• Create ext4 / xfs / vfat filesystems with the mkfs family
• Build a swap area with mkswap and swapon
• Inspect disk state accurately with lsblk / blkid / partprobe

This is the core of LPIC-1 objective 104.1 "Create partitions and filesystems". It covers the full flow of dividing a disk and making it usable.

What Do You Decide First?

The first decision is "MBR or GPT", because it changes which partition-editing tool you use. Choose GPT for disks larger than 2TB or when you need more than four primary partitions.

To make a disk usable, you normally go through three stages. Skipping the order means you cannot mount.

How Do MBR and GPT Differ?

MBR is the older scheme with a limit of four primary partitions. GPT is the newer scheme that supports large disks and many partitions.

When MBR needs five or more regions, you create 3 primary partitions plus 1 extended partition, and place logical partitions inside the extended one. GPT removes this constraint and treats all partitions equally.

Steps

Step 1: Check disk layout with lsblk

lsblk

NAME   MAJ:MIN RM  SIZE RO TYPE MOUNTPOINTS
sda      8:0    0   50G  0 disk
├─sda1   8:1    0   49G  0 part /
└─sda2   8:2    0    1G  0 part [SWAP]
sdb      8:16   0   20G  0 disk

lsblk shows block devices and partitions hierarchically. Here sdb is still unpartitioned (no sdb1 child). Mistaking the target device name destroys existing data, so always check first.

Step 2: Create an MBR partition with fdisk

fdisk /dev/sdb

Command (m for help): n
Partition type
   p   primary (0 primary, 0 extended, 4 free)
   e   extended
Select (default p): p
Partition number (1-4, default 1): 1
First sector (2048-41943039, default 2048):
Last sector, +/-sectors or +/-size{K,M,G,T,P} (default 41943039): +10G

Created a new partition 1 of type 'Linux' and of size 10 GiB.

Command (m for help): w
The partition table has been altered.

The main fdisk subcommands are n (new), p (print table), d (delete), t (change type), w (write and quit), and q (quit without saving). Use n to specify type, number, and size, then commit with w.

Step 3: Use gdisk for GPT, parted for general use

gdisk /dev/sdb
parted /dev/sdb mklabel gpt
parted /dev/sdb mkpart primary ext4 1MiB 10GiB

Command (? for help): n
Partition number (1-128, default 1): 1
First sector (...):
Last sector (...): +10G
Current type is 8300 (Linux filesystem)
Command (? for help): w

GPT disks are edited interactively with gdisk. Its operation set resembles fdisk, using n (create), d (delete), and w (write). parted supports both MBR and GPT and can run mklabel (create the table type) and mkpart (create a partition) on one line, making it well suited to scripting.

Step 4: Reload the table into the kernel with partprobe

partprobe /dev/sdb
lsblk /dev/sdb

NAME   MAJ:MIN RM SIZE RO TYPE MOUNTPOINTS
sdb      8:16   0  20G  0 disk
└─sdb1   8:17   0  10G  0 part

Even after rewriting the partition table, a kernel may still hold the old information for a disk in use. partprobe asks the kernel to reread the partition table. Confirm with lsblk that the new sdb1 is recognized.

Step 5: Create a filesystem with mkfs

mkfs.ext4 /dev/sdb1
blkid /dev/sdb1

mke2fs 1.46.5 (30-Dec-2021)
Creating filesystem with 2621440 4k blocks and 655360 inodes
Filesystem UUID: 3f29c0a1-...-9b2e4d
Writing superblocks and filesystem accounting information: done

/dev/sdb1: UUID="3f29c0a1-...-9b2e4d" TYPE="ext4"

mkfs.ext4 creates an ext4 filesystem. mkfs.xfs (XFS) and mkfs.vfat (FAT, -F 32 for FAT32) work the same way. mkfs.ext4 internally calls mke2fs. After creation, check the UUID and filesystem type with blkid. The UUID is used for persistent mounts in /etc/fstab.

Step 6: Create a swap area with mkswap

mkswap /dev/sdb2
swapon /dev/sdb2
swapon --show

Setting up swapspace version 1, size = 2 GiB
no label, UUID=8a1f...e07c

NAME      TYPE      SIZE USED PRIO
/dev/sdb2 partition   2G   0B   -2

A swap partition is initialized with mkswap, not mkfs. Enable it with swapon and disable it with swapoff. Confirm active swap with swapon --show or free -h. Note that a swap area also fails on swapon unless you run mkswap first.

How Do You Choose ext / xfs / vfat / btrfs?

For a general-purpose Linux filesystem, ext4 is a safe default. Use xfs for large capacity and high concurrency, and vfat for Windows sharing or the EFI system partition.

ext2/3/4 are compatible by lineage, with mke2fs as the common implementation. Note operationally that xfs cannot be shrunk once created (grow only). btrfs is a relatively new filesystem with built-in snapshots and RAID features; for LPIC-1, an overview-level understanding is enough.

Troubleshooting

Symptom: mount reports wrong fs type

Cause: You created the partition but did not create a filesystem with mkfs

Check:

blkid /dev/sdb1

Fix: If blkid shows no TYPE=, it is unformatted. Create a filesystem with mkfs.ext4 /dev/sdb1 or similar.

Symptom: fdisk cannot create a fifth primary partition

Cause: MBR is limited to four primary partitions

Check:

fdisk -l /dev/sdb

Fix: Create an extended partition and place logical partitions inside it. To avoid the limit entirely, switch to GPT with parted ... mklabel gpt (existing data is lost).

Symptom: A partition does not appear in lsblk

Cause: The kernel holds the old partition table

Check:

lsblk /dev/sdb

Fix: Run partprobe /dev/sdb to make the kernel reread the table. If it still does not appear, reboot.

Symptom: swapon fails with Invalid argument

Cause: You did not run mkswap on the target partition

Check:

blkid /dev/sdb2

Fix: Initialize it as swap with mkswap /dev/sdb2, then run swapon /dev/sdb2.

Completion Checklist

• [ ] Confirmed with lsblk that you targeted the right device
• [ ] Created the partition with fdisk / gdisk / parted and wrote it with w
• [ ] Reloaded the table into the kernel with partprobe
• [ ] Formatted with mkfs.ext4 (or the mkfs for your purpose)
• [ ] Enabled swap with mkswap then swapon
• [ ] Checked UUID and filesystem type with blkid

Summary

Creating partitions and filesystems is the entry point to making a disk usable. Next, proceed to mounting that filesystem and making it persistent in /etc/fstab to complete your understanding.

Next Reading

• Mounting and Managing Filesystems
• FHS and Finding Files
• Basic File Management