Master Linux Disk Partitioning: From MBR Basics to Automated XFS Setup

1 Primary and Logical Partitions

1.1 Linux partitioning basics

Disk partitioning formats the disk and sets up the Master Boot Record (MBR) and its backup.

MBR consists of a 446‑byte boot loader, a partition table with four 16‑byte entries, and a 2‑byte boot signature (0xAA55).

Partition numbers: primary 1‑4, logical start at 5.

Linux requires logical partitions to reside within an extended partition.

Primary partitions are used for booting (/boot); extended partitions are containers; data is stored in primary or logical partitions.

Use fdisk for partitioning and formatting.

Maximum of four primary+extended partitions; only one extended partition; logical partitions can be multiple.

1.2 Disk management commands

fdisk – Linux partition table tool

# Common operations
fdisk -l   # list partitions
n          # add new partition
p          # primary
e          # extended
w          # write and exit
q          # quit without saving
d          # delete
t          # change type

1.3 View disks

ls /dev/sd*   # list disk devices

Device letters a‑z represent disk numbers (sda, sdb, …). n indicates partition number.

1.4 Creating a primary partition (demo)

1.4.1 Add disk and create primary partition

ls /dev/sd*
fdisk /dev/sdb
# create primary partition of 5 GiB
n
p
1
<enter>
+5G
w

1.4.2 Verify partition

fdisk -l /dev/sdb

1.4.3 Format to XFS

mkfs.xfs /dev/sdb1

1.4.4 Mount locally

mkdir /xfs_du
mount /dev/sdb1 /xfs_du

1.4.5 Check mount

df -h

1.4.6 Enable auto‑mount at boot

echo "/dev/sdb1 /xfs_du xfs defaults 0 0" >> /etc/fstab
# alternative method
echo "mount /dev/sdb1 /xfs_du" >> /etc/rc.local
chmod +x /etc/rc.d/rc.local

1.5 fdisk demo – create logical partition

1.5.1 Add extended partition

fdisk /dev/sdb
n
e
+5G
w

1.5.2 Create logical partition

fdisk /dev/sdb
n
l
+2G
w

1.5.3 Create filesystem on logical partition

mkfs.xfs /dev/sdb5

1.5.4 Auto‑mount logical partition

echo "mount /dev/sdb5 /xfs_du" >> /etc/rc.local

2 Bad‑disk recovery (disks >8 TB)

2.1 Identify faulty disk

2.1.1 List SCSI devices

sudo lsscsi

2.1.2 IO test to locate bad disk

dd oflag=direct if=/dev/zero of=wtest_find_error_disk bs=64k count=100k

2.2 Initialize new disk, partition, format

2.2.1 List current partitions

fdisk -l   # note: use GPT for >2 TB disks

2.2.2 Check partition table type

parted /dev/sdX print list

2.2.3 Create partition table

sudo parted -s /dev/sdX mklabel gpt   # or msdos

2.2.4 Create partition

sudo parted -s /dev/sdX mkpart primary 0% 100%

2.2.5 Verify

fdisk -l

2.2.6 Format filesystem

sudo mkfs.xet4 /dev/sdX1

3 Swap partition

Swap provides virtual memory when physical RAM is insufficient.

3.1 Create swap in a local directory

3.1.1 Create directory

mkdir /swap

3.1.2 Create empty file

dd if=/dev/zero of=/swap/swap bs=2M count=2014

3.1.3 Format as swap

mkswap /swap/swap

3.1.4 Add to /etc/fstab for auto‑mount

echo "/swap/swap swap swap defaults 0 0" >> /etc/fstab

3.1.5 Set permissions and mount

chmod 0600 /swap/swap
mount -a

3.1.6 Enable swap

swapon -a

3.1.7 Disable swap

swapoff -a