How to Partition Linux Disks for Three Common Scenarios

Linux Disk Partitioning: Three Common Scenarios

Scenario 1 – Mount a New Partition to a Directory

First, inspect the target disk:

lsblk /dev/sdb
NAME   MAJ:MIN RM  SIZE RO TYPE MOUNTPOINT
sdb    8:16   0  32G  0 disk
├─sdb1 8:17   0 200M 0 part /boot/eif

Create a new primary partition (sdb2) of about 15 GB using fdisk:

fdisk /dev/sdb
n   # new partition
p   # primary
2   # partition number
<Enter>   # default start sector
+15G   # size
w   # write changes

Format the new partition (ext4 in this example) and mount it:

mkfs.ext4 /dev/sdb2
mkdir /mnt/sdb2
mount /dev/sdb2 /mnt/sdb2

Verify the mount:

df -hT
Filesystem     Type  Size Used Avail Use% Mounted on
/dev/sdb2      ext4   15G  41M   14G   1% /mnt/sdb2

Scenario 2 – Expand a Subdirectory Using a Symbolic Link

When a subdirectory needs more space, create a new partition, format it, mount it at a temporary location, and then link the original subdirectory to the new mount point with a symbolic link, effectively extending storage without moving files.

Scenario 3 – Expand the Root Filesystem

For a system using an MBR disk (e.g., /dev/sda) with the root partition (/dev/sda7) formatted as XFS, the following steps enlarge the root filesystem:

1. Ensure the root partition is the last one on the disk and note its size with fdisk -l:

fdisk -l /dev/sda
... (output showing /dev/sda7 as the last partition) ...

2. Refresh the kernel partition table:

sudo partprobe /dev/sda

3. Verify the filesystem type:

blkid /dev/sda7
/dev/sda7: UUID="f7c7645e-5d67-43f8-ba7e-5c9f019d980a" TYPE="xfs"

4. Grow the XFS filesystem to use the newly allocated space:

sudo xfs_growfs /dev/sda7

5. Confirm the expanded size:

df -h
Filesystem     Size Used Avail Use% Mounted on
/dev/sda7       152G  66M  152G   1% /