Disk Management in Practice — lsblk, df, du, fdisk, LVM

# Block device list (including mount points)
lsblk

# Filesystem usage
df -h

# inode usage (file count limit issues)
df -i

# Usage by directory (one level)
du -sh /*

# Sort by size, largest first
du -sh /var/* | sort -rh | head -10

# Identify the new disk (usually /dev/sdb or /dev/nvme1n1)
lsblk
fdisk -l /dev/sdb

# Create a partition (interactive)
fdisk /dev/sdb
# → n (new partition), p (primary), 1 (number), Enter, Enter (whole disk), w (write)

# GPT partition (2TB or larger)
parted /dev/sdb mklabel gpt
parted /dev/sdb mkpart primary ext4 0% 100%

# Format
mkfs.ext4 /dev/sdb1

# Mount
mkdir /data
mount /dev/sdb1 /data

# Auto-mount on boot (/etc/fstab)
echo "UUID=$(blkid -s UUID -o value /dev/sdb1) /data ext4 defaults 0 2" >> /etc/fstab
mount -a  # Verify fstab took effect

# Check current LVM status
pvs    # Physical volumes
vgs    # Volume groups
lvs    # Logical volumes

# Initialize the new disk as a physical volume
pvcreate /dev/sdb

# Add to an existing volume group
vgextend ubuntu-vg /dev/sdb

# Extend the logical volume (all free space)
lvextend -l +100%FREE /dev/ubuntu-vg/ubuntu-lv

# Grow the filesystem (ext4)
resize2fs /dev/ubuntu-vg/ubuntu-lv

# For XFS
xfs_growfs /

# SMART information
apt install smartmontools
smartctl -a /dev/sda

# Real-time I/O statistics
iostat -x 1 5

# Disk read/write speed test
dd if=/dev/zero of=/tmp/test bs=1M count=1024 oflag=direct

# Purge journald logs older than 2 weeks
journalctl --vacuum-time=2w

# Clean apt cache
apt autoremove && apt clean

# Remove unused Docker resources
docker system prune -a

# Delete old log files
find /var/log -name "*.gz" -mtime +30 -delete