Block Storage

Manage block storage volumes including LVM, cloud-based EBS, filesystem creation, snapshots, and RAID configurations. Covers the full lifecycle from provisioning raw disks to extending volumes in production.

When to Use

• Adding, partitioning, or formatting new disks on Linux servers
• Managing LVM logical volumes for flexible storage allocation
• Provisioning and attaching cloud block storage (AWS EBS)
• Creating and restoring snapshots for backup or migration
• Configuring software RAID for redundancy or performance
• Extending existing volumes without downtime

Prerequisites

• Root or sudo access on the target system
• lvm2 package installed for LVM operations
• mdadm package installed for software RAID
• AWS CLI configured for EBS operations
• Understanding of the workload's I/O characteristics (IOPS, throughput)

Disk Discovery and Partitioning

# List all block devices
lsblk
lsblk -f    # Show filesystem types and mount points

# Show detailed disk information
fdisk -l /dev/sdb

# Identify disk model and health (requires smartmontools)
smartctl -a /dev/sda
smartctl -H /dev/sda    # Quick health check

# Create a GPT partition table and a single partition
parted /dev/sdb mklabel gpt
parted /dev/sdb mkpart primary ext4 0% 100%

# Alternative: use fdisk for MBR partitioning
fdisk /dev/sdb
# n -> new partition, p -> primary, Enter defaults, w -> write

# Inform the kernel of partition table changes
partprobe /dev/sdb

# Wipe filesystem signatures (prepare for LVM or RAID)
wipefs -a /dev/sdb1

Filesystem Creation and Management

# Create an ext4 filesystem
mkfs.ext4 /dev/sdb1

# Create an ext4 filesystem with label and reserved block tuning
mkfs.ext4 -L appdata -m 1 /dev/sdb1    # 1% reserved blocks (default is 5%)

# Create an XFS filesystem (recommended for large volumes)
mkfs.xfs /dev/sdb1

# Create an XFS filesystem with label
mkfs.xfs -L appdata /dev/sdb1

# Mount the filesystem
mkdir -p /data
mount /dev/sdb1 /data

# Add persistent mount to fstab (use UUID for reliability)
blkid /dev/sdb1    # Get the UUID
echo 'UUID=xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx  /data  ext4  defaults,noatime  0  2' >> /etc/fstab

# Mount all entries in fstab
mount -a

# Check and repair a filesystem (unmount first)
umount /data
fsck.ext4 -y /dev/sdb1
xfs_repair /dev/sdb1    # For XFS

# Resize ext4 (can grow online while mounted)
resize2fs /dev/sdb1

# Resize XFS (must be mounted to grow)
xfs_growfs /data

# Check filesystem usage
df -hT

LVM Management

Creating an LVM Stack

# Step 1: Create physical volumes
pvcreate /dev/sdb /dev/sdc

# View physical volumes
pvs
pvdisplay /dev/sdb

# Step 2: Create a volume group from physical volumes
vgcreate data_vg /dev/sdb /dev/sdc

# View volume groups
vgs
vgdisplay data_vg

# Step 3: Create logical volumes
# Fixed size
lvcreate -L 100G -n app_lv data_vg

# Use percentage of free space
lvcreate -l 50%FREE -n logs_lv data_vg

# Use all remaining space
lvcreate -l 100%FREE -n backup_lv data_vg

# View logical volumes
lvs
lvdisplay /dev/data_vg/app_lv

# Step 4: Create filesystem and mount
mkfs.ext4 /dev/data_vg/app_lv
mkdir -p /data/app
mount /dev/data_vg/app_lv /data/app

# Add to fstab
echo '/dev/data_vg/app_lv  /data/app  ext4  defaults,noatime  0  2' >> /etc/fstab

Extending Volumes (Online)

# Extend a logical volume by 20 GB
lvextend -L +20G /dev/data_vg/app_lv

# Extend to fill all free space in the VG
lvextend -l +100%FREE /dev/data_vg/app_lv

# Grow the ext4 filesystem (online, no unmount needed)
resize2fs /dev/data_vg/app_lv

# Grow XFS filesystem (online)
xfs_growfs /data/app

# Combined: extend LV and resize filesystem in one command
lvextend -L +20G --resizefs /dev/data_vg/app_lv

Adding a New Disk to an Existing VG

# Add a new physical volume
pvcreate /dev/sdd

# Extend the volume group
vgextend data_vg /dev/sdd

# Now extend any logical volume using the new space
lvextend -l +100%FREE --resizefs /dev/data_vg/app_lv

LVM Snapshots

# Create a snapshot (requires free space in VG)
lvcreate -L 10G -s -n app_snap /dev/data_vg/app_lv

# Mount the snapshot read-only for backup
mkdir -p /mnt/snapshot
mount -o ro /dev/data_vg/app_snap /mnt/snapshot

# Perform backup from the snapshot
tar czf /backup/app-$(date +%Y%m%d).tar.gz -C /mnt/snapshot .

# Unmount and remove the snapshot when done
umount /mnt/snapshot
lvremove -f /dev/data_vg/app_snap


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