Exam weight: 2 — LPIC-1 v5, Exam 101
What You Need to Know
- Manage MBR and GPT partition tables.
- Create filesystems with
mkfs: ext2, ext3, ext4, XFS, VFAT, exFAT. - Basic understanding of Btrfs: multi-device, compression, subvolumes.
Key utilities: fdisk, gdisk, parted, mkfs, mkswap.
Partitions and Partition Tables
A partition is a logical slice of a physical disk described by an entry in the partition table. Each partition appears to the OS as a separate disk. In Linux partitions become device files: /dev/sda1, /dev/sda2.
All disk management operations require root privileges.
MBR vs GPT
MBR
MBR (Master Boot Record) dates from PC-DOS 2.0 in 1983. The partition table lives in the first sector of the disk alongside the bootloader (usually GRUB on Linux).
Limitations:
- Maximum disk size: 2 TB.
- No more than 4 primary partitions.
GPT
GPT (GUID Partition Table) removes MBR’s limits. Disk size is practically unlimited. Up to 128 partitions by default. Used on modern UEFI machines.
Each GPT disk gets a 128-bit GUID. GPT stores a backup header and partition table at the end of the disk for recovery.
Comparison
| Parameter | MBR | GPT |
|---|---|---|
| Year | 1983 | late 1990s |
| Max disk size | 2 TB (often cited as 2.2 TB) | up to 9.4 ZB |
| Max partitions | 4 primary | 128 by default |
| Firmware | BIOS | UEFI |
| Backup table | no | yes, at disk end |
| Disk identifier | 32-bit | 128-bit GUID |
fdisk — MBR Partition Editor
fdisk /dev/sda
Changes are held in memory until you write with w. Exit without saving: q.
Key Commands
| Command | Action |
|---|---|
p | print partition table |
n | create new partition |
d | delete partition |
t | change partition type |
l | list known partition types |
F | show free (unpartitioned) space |
w | write changes and exit |
q | quit without saving |
Primary vs Extended Partitions
MBR supports at most 4 primary partitions. To have more, create one extended partition as a container for logical partitions inside.
Creating a Partition
Command (m for help): n
Select (default p): p
Partition number (1-4, default 1): 1
First sector (2048-3903577, default 2048): 2048
Last sector or +size{K,M,G,T,P}: +1G
Free Space and Contiguity
Key point: the maximum size of a new partition is limited by the largest contiguous free block, not the total free space. Two 512 MB gaps do not allow a 1 GB partition.
Changing Partition Type
Command t → partition number → hex code. Common codes:
83: Linux82: Linux swap
gdisk — GPT Partition Editor
gdisk mirrors fdisk for GPT disks.
gdisk /dev/sdb
Command p shows the disk GUID and total free space in the header. Type codes are four-digit hex:
8300: Linux filesystem8200: Linux swap
Command s renumbers partitions after a deletion. Recovery menu (r) provides tools to rebuild headers, convert MBR↔GPT.
GPT advantage: a new partition can use any free space regardless of physical location — no contiguity requirement.
Creating Filesystems
mkfs without a type flag creates ext2 by default.
ext2 / ext3 / ext4
mkfs.ext2, mkfs.ext3, mkfs.ext4 are all symlinks to mke2fs.
mkfs.ext4 /dev/sdb1
mke2fs -t ext4 /dev/sdb1 # equivalent
Key options:
| Option | Description |
|---|---|
-b SIZE | block size: 1024, 2048, or 4096 |
-c | check for bad blocks |
-c -c | thorough (slow) bad block check |
-L LABEL | volume label (≤16 chars) |
-U ID | UUID: literal, clear, random, or time |
-n | dry run — no writes |
-d DIR | pre-populate filesystem from directory |
-F | force creation |
-q | quiet |
XFS
High-performance journaling filesystem from SGI (1993). Default on RHEL 7+. Package: xfsprogs.
mkfs.xfs /dev/sda1
Key options:
| Option | Description |
|---|---|
-b size=N | block size (512–65536, default 4096) |
-m crc=0/1 | CRC32c metadata checksums (default on) |
-f | force (overwrite existing filesystem) |
-l logdev=DEV | external log device |
-L LABEL | label (≤12 chars) |
-N | dry run |
VFAT / FAT
mkfs.fat (alias mkfs.vfat). Used for small flash drives and legacy devices.
- FAT16: volume ≤ 4 GB, file ≤ 2 GB
- FAT32: volume ≤ 2 PB, file ≤ 4 GB
mkfs.fat /dev/sdc1
Options: -F SIZE (FAT size: 12, 16, 32), -n NAME (label ≤11 chars), -c (bad blocks).
exFAT
Microsoft exFAT (2006). Max file: 16 EB. Max volume: 128 PB. Standard for SDXC cards > 32 GB.
mkfs.exfat /dev/sdb2
Options: -n NAME (label ≤15 chars), -i VOL_ID (32-bit volume ID).
Btrfs
B-Tree Filesystem, developed since 2007. Default on SUSE.
Features: multi-device RAID (0/1/5/6/10), transparent compression, snapshots, subvolumes, deduplication, copy-on-write.
mkfs.btrfs /dev/sdb1
mkfs.btrfs -d raid1 -m raid1 /dev/sdb /dev/sdc # mirror
Subvolumes share free space with the parent filesystem (unlike partitions which reserve space upfront):
btrfs subvolume create /mnt/disk/BKP
btrfs subvolume snapshot /mnt/disk /mnt/disk/snap
btrfs subvolume snapshot -r /mnt/disk /mnt/disk/snap # read-only
mount -t btrfs -o subvol=BKP /dev/sdb1 /mnt/bkp
Compression algorithms: ZLIB, LZO, ZSTD.
mount -o compress /dev/sdb1 /mnt/disk
GNU Parted
Works with both MBR and GPT.
Warning: parted applies changes immediately — there is no w command.
parted /dev/sdb
Key Commands
| Command | Action |
|---|---|
mklabel TYPE | create partition table (msdos or gpt) |
mkpart PARTTYPE FSTYPE START END | create partition |
rm N | delete partition N |
rescue START END | recover a deleted partition |
resizepart N END | move end of partition N |
print free | show free space |
mkpart
(parted) mkpart primary ext4 1m 100m
(parted) mkpart primary linux-swap 301m 800m
FSTYPE is a hint only — parted does not create the filesystem. Always run mkfs afterward.
Rescue
Scans the disk between START and END for filesystem signatures. Only finds partitions that had a filesystem.
(parted) rescue 90m 210m
Resizing
Shrink (order matters — reversing it destroys data):
- Shrink filesystem:
resize2fs /dev/sdb3 88m - Move partition end:
resizepart 3 300m
Grow:
- Move partition end:
resizepart N NEW_END - Grow filesystem:
resize2fs /dev/sdbN
resize2fs -M shrinks the filesystem to the minimum size needed for the current data.
Swap
Setup
Change type in fdisk: t → 82; in gdisk: t → 8200; in parted: specify linux-swap as FSTYPE.
Always run mkswap before swapon — without it you get read swap header failed.
mkswap /dev/sda2
swapon /dev/sda2
swapoff /dev/sda2
swapon -s # list active swap
cat /proc/swaps
Swap File
dd if=/dev/zero of=myswap bs=1M count=1024
mkswap myswap
swapon myswap
Add to /etc/fstab to persist across reboots. Recommended permissions: 0600, owner root.
Quick Reference
Partition Type Codes
| Type | fdisk (MBR) | gdisk (GPT) |
|---|---|---|
| Linux filesystem | 83 | 8300 |
| Linux swap | 82 | 8200 |
Filesystem Commands
| Command | Filesystem |
|---|---|
mkfs DEV | ext2 (default) |
mkfs.ext2/3/4 DEV | ext2/3/4 |
mke2fs -t TYPE DEV | ext alternative |
mkfs.xfs DEV | XFS |
mkfs.fat / mkfs.vfat DEV | FAT/VFAT |
mkfs.exfat DEV | exFAT |
mkfs.btrfs DEV [DEV2...] | Btrfs |
Exam Questions
- Max partitions in MBR? → 4 primary.
- Max disk size in MBR? → 2 TB (often cited as 2.2 TB).
- Max partitions in GPT by default? → 128.
- Linux swap type code in fdisk? → 82.
- Linux swap type code in gdisk? → 8200.
- Command to change type in fdisk? →
t. - parted command for MBR table? →
mklabel msdos. - Default filesystem created by
mkfsalone? → ext2. - Does
mkpartin parted create the filesystem? → No, only sets a type flag. - XFS utility package? → xfsprogs.
- Btrfs compression algorithms? → ZLIB, LZO, ZSTD.
- mke2fs option for bad block check? →
-c. - Difference between
mkfs.fatandmkfs.vfat? → Same utility, vfat is an alias. - Max file size on FAT32? → 4 GB.
- Correct order to shrink an ext4 partition? →
resize2fsfirst, thenresizepart. - What does
resize2fs -Mdo? → Shrinks filesystem to minimum size for current data. - Error
read swap header failed— cause? →mkswapwas not run beforeswapon. - What does parted
rescuefind? → Partitions that had a filesystem — empty partitions are not found. - Difference between Btrfs subvolume and a partition? → Subvolume shares free space with parent; partition reserves space upfront.
- How to find UUID and label of a filesystem? →
lsblk -f.
Exercises
Exercise 1 — Partition table for a 3 TB disk
A 3 TB disk needs three 1 GB partitions. Which partition table type should you use, and why?
Answer
GPT. MBR is limited to 2 TB disks, so a 3 TB disk cannot be fully addressed by MBR.
Exercise 2 — Free space in gdisk
How do you see how much free space remains on a disk in gdisk?
Answer
Command p (print). The header above the partition list shows total free space:
Total free space is 1282071 sectors (626.0 MiB)
Exercise 3 — Create ext3 with bad block check, label, and random UUID
Create ext3 on /dev/sdc1 with bad block check, label MyDisk, and a random UUID.
Answer
mkfs.ext3 -c -L MyDisk -U random /dev/sdc1
Alternative via mke2fs:
mke2fs -t ext3 -c -L MyDisk -U random /dev/sdc1
Exercise 4 — Create partition in parted
In parted, create a 300 MB ext4 partition starting at 500 MB.
Answer
(parted) mkpart primary ext4 500m 800m
Remember: parted only sets a type flag — it does not create the filesystem. After exiting parted, run mkfs.ext4 /dev/sdXN separately.
Exercise 5 — Btrfs RAID1 on two 20 GB partitions
Two 20 GB partitions. Combine them into one Btrfs with mirroring. What is the usable size?
Answer
mkfs.btrfs -d raid1 -m raid1 /dev/sda1 /dev/sdb1
Usable size: 20 GB — one partition mirrors the other.
Exercise 6 — 600 MB partition on a fragmented MBR disk
An MBR disk (1.9 GB) has two existing partitions: /dev/sdb1 (512 MB) and /dev/sdb3 (512 MB), with free space in the gaps between them. Can you create a new 600 MB partition?
Answer
No. Total free space is about 1 GB, but the largest contiguous free block is only 512 MB. A partition cannot span a gap — fdisk rejects it with Value out of range.
Use F in fdisk to inspect the free space layout.
Exercise 7 — Shrink partition to minimum size
The first partition on /dev/sdc is 1 GB with ext4, containing about 256 MB of files. Shrink it to the minimum needed size.
Answer
Two-step operation — filesystem first, then partition boundary.
Step 1 — shrink the filesystem to fit actual data:
resize2fs -M /dev/sdc1
Step 2 — move the partition end in parted:
(parted) resizepart 1 241M
Order is critical: always shrink the filesystem before moving the partition boundary. Reversing the order destroys data.
Exercise 8 — swapon fails with “read swap header failed”
A partition was created with mkpart primary linux-swap 0 1024M, then swapon /dev/sdb1 fails with read swap header failed. What is wrong and how do you fix it?
Answer
mkpart creates the partition but does not write the swap header. Always run mkswap before swapon:
mkswap /dev/sdb1
swapon /dev/sdb1
Exercise 9 — Recover accidentally deleted partition in parted
A disk had an EFI partition (250 MB), swap (4 GB), and a third partition (10 GB). The third was accidentally deleted. How do you recover it?
Answer
Use rescue with estimated boundaries.
Calculate: 250 MB (EFI) + 4×1024 MB (swap) = 4346 MB — start. End: 4346 + 10×1024 = 14 586 MB.
(parted) rescue 4346m 14586m
Give a small margin in both directions — disk geometry can shift boundaries slightly. rescue only finds partitions that had a filesystem.
Exercise 10 — Activate /dev/sda3 as swap using fdisk
Turn an unused 4 GB partition /dev/sda3 into active swap.
Answer
Step 1 — change partition type to Linux Swap in fdisk:
Command (m for help): t
Partition number (1-3, default 3): 3
Hex code (type L to list all codes): 82
Changed type of partition 'Linux' to 'Linux swap / Solaris'.
Command (m for help): w
Step 2 — write the swap header:
mkswap /dev/sda3
Step 3 — activate swap:
swapon /dev/sda3
LPIC-1 Study Notes | Topic 104: Devices, Linux Filesystems, Filesystem Hierarchy Standard