Scenario

The server has unmounted partitions that are not being used and could be utilized for additional storage.

Task

Identify unmounted partitions that are safe to use (avoiding system-critical partitions like /, /boot, /boot/efi, or swap), create an ext4 filesystem on one with a label data_extra, mount it at /mnt/test, and verify it's accessible.

Example

# Before (unmounted partition unused)
Block devices scanned, unmounted partitions found
loop0p2: 20GB unmounted, no filesystem

# After (partition formatted and mounted)
Filesystem created: ext4 with label=data_extra on /dev/loop0p2
Mounted at: /mnt/test
/dev/loop0p2 on /mnt/test type ext4 (rw,relatime)
Partition ready for use

Step 1: List block devices with filesystem information

lsblk -f

Shows mountpoints, filesystem type (FSTYPE), and labels. Avoid system-critical partitions: / (root), /boot, /boot/efi, [SWAP], and small devices (< 10M). Unmounted/unused partitions have blank FSTYPE.

Step 2: Identify the safe unmounted partition

Find a partition with reasonable size, no MOUNTPOINT, no FSTYPE, and not on the system disk. In this environment, /dev/loop0p2 is the safe target.

Step 3: Create ext4 filesystem with label

sudo mkfs.ext4 -L data_extra /dev/loop0p2

The -L data_extra flag assigns a human-readable label. Warning: this destroys any existing data on the partition.

Step 4: Create mount point and mount the partition

sudo mkdir -p /mnt/test
sudo mount /dev/loop0p2 /mnt/test

The -p flag creates parent directories if needed. This is a temporary mount (won't persist after reboot).

Step 5: Verify the mount

df -h /mnt/test
mount | grep /mnt/test

df -h shows disk space in human-readable format. mount | grep shows mount options.

Step 6: Verify the label and test write access

lsblk -f | grep loop0p2
sudo touch /mnt/test/test_file
ls -l /mnt/test/

Confirms label was applied and filesystem is writable.