How to Manage Storage Pools¶

This guide shows you how to effectively manage storage pools throughout their lifecycle - from creation to maintenance to cleanup.

🎯 Goal¶

Learn to manage storage pools for:

Creating and deleting storage pools
Resizing and expanding pools
Moving storage between pools
Monitoring storage usage and performance
Implementing storage policies

📋 Prerequisites¶

Completed Storage Pool Creation tutorial
Basic understanding of storage concepts
Administrative access to KVM host
Existing storage pools to manage

🛠️ Managing Pool Lifecycle¶

Create New Storage Pools¶

Directory Pool Creation¶

# Create directory
sudo mkdir -p /var/lib/libvirt/images/new-pool
sudo chown root:root /var/lib/libvirt/images/new-pool
sudo chmod 755 /var/lib/libvirt/images/new-pool

# Define pool
sudo virsh pool-define-as new-pool dir - - - - /var/lib/libvirt/images/new-pool

# Start and autostart
sudo virsh pool-start new-pool
sudo virsh pool-autostart new-pool

LVM Pool Creation¶

# Create logical volume
sudo lvcreate -L 100G -n lv_new_pool vg_storage

# Define LVM pool
sudo virsh pool-define-as new-lvm-pool logical - - vg_storage /dev/vg_storage

# Start pool
sudo virsh pool-start new-lvm-pool
sudo virsh pool-autostart new-lvm-pool

Delete Storage Pools¶

⚠️ Warning: This will destroy all data in the pool!

# Stop the pool
sudo virsh pool-destroy pool-name

# Undefine the pool
sudo virsh pool-undefine pool-name

# Remove directory (for directory pools)
sudo rm -rf /var/lib/libvirt/images/pool-name

# Remove LVM volume (for LVM pools)
sudo lvremove /dev/vg_storage/lv_pool_name

📊 Monitoring Storage Usage¶

Check Pool Status¶

# List all pools with status
sudo virsh pool-list --all

# Get detailed pool information
sudo virsh pool-info pool-name

# Check pool capacity and usage
sudo virsh pool-info pool-name | grep -E "(Capacity|Allocation|Available)"

Monitor Disk Usage¶

# Check filesystem usage (directory pools)
df -h /var/lib/libvirt/images/

# Check LVM usage (LVM pools)
sudo vgdisplay vg_storage
sudo lvdisplay /dev/vg_storage/lv_pool

# List volumes in pool
sudo virsh vol-list pool-name

Storage Performance Monitoring¶

# Monitor I/O statistics
iostat -x 1 5

# Check for storage bottlenecks
iotop -o

# Monitor specific pool performance
sudo virsh domblkstat VM_NAME DISK_PATH

🔄 Pool Maintenance Operations¶

Refresh Pool Contents¶

# Refresh pool to detect external changes
sudo virsh pool-refresh pool-name

# Verify volumes are detected
sudo virsh vol-list pool-name

Resize Storage Pools¶

Expand Directory Pool¶

# For directory pools, expand the underlying filesystem
sudo resize2fs /dev/mapper/vg-lv_storage

# Refresh the pool
sudo virsh pool-refresh pool-name

Expand LVM Pool¶

# Extend the logical volume
sudo lvextend -L +50G /dev/vg_storage/lv_pool

# Refresh the pool
sudo virsh pool-refresh pool-name

Move Volumes Between Pools¶

# Copy volume to new pool
sudo virsh vol-clone --pool source-pool volume-name target-pool

# Verify copy
sudo virsh vol-info volume-name target-pool

# Remove from source pool (after verification)
sudo virsh vol-delete volume-name source-pool

🔒 Storage Security and Permissions¶

Set Proper Permissions¶

# For directory pools
sudo chown -R root:root /var/lib/libvirt/images/pool-name
sudo chmod -R 755 /var/lib/libvirt/images/pool-name

# Set SELinux contexts
sudo setsebool -P virt_use_nfs 1
sudo restorecon -R /var/lib/libvirt/images/

Secure Storage Access¶

# Create dedicated storage group
sudo groupadd libvirt-storage

# Add users to storage group
sudo usermod -a -G libvirt-storage username

# Set group permissions
sudo chgrp -R libvirt-storage /var/lib/libvirt/images/pool-name
sudo chmod -R g+rw /var/lib/libvirt/images/pool-name

📈 Storage Optimization¶

Performance Tuning¶

I/O Scheduler Optimization¶

# Check current scheduler
cat /sys/block/sda/queue/scheduler

# Set optimal scheduler for SSDs
echo mq-deadline | sudo tee /sys/block/sda/queue/scheduler

# Make permanent in /etc/udev/rules.d/60-scheduler.rules
echo 'ACTION=="add|change", KERNEL=="sd[a-z]", ATTR{queue/rotational}=="0", ATTR{queue/scheduler}="mq-deadline"' | sudo tee /etc/udev/rules.d/60-scheduler.rules

Storage Pool Optimization¶

# Enable discard for SSD pools
sudo virsh pool-edit pool-name
# Add: <features><discard/></features>

# Set optimal allocation policies
sudo virsh pool-edit pool-name
# Modify allocation and capacity settings

Capacity Planning¶

Monitor Growth Trends¶

# Create monitoring script
cat > /usr/local/bin/storage-monitor.sh << 'EOF'
#!/bin/bash
for pool in $(virsh pool-list --name); do
    echo "Pool: $pool"
    virsh pool-info $pool | grep -E "(Capacity|Allocation|Available)"
    echo "---"
done
EOF

sudo chmod +x /usr/local/bin/storage-monitor.sh

# Run monitoring
sudo /usr/local/bin/storage-monitor.sh

Set Up Alerts¶

# Create alert script for low space
cat > /usr/local/bin/storage-alert.sh << 'EOF'
#!/bin/bash
THRESHOLD=90
for pool in $(virsh pool-list --name); do
    USAGE=$(virsh pool-info $pool | grep "Allocation" | awk '{print $2}' | sed 's/[^0-9.]//g')
    CAPACITY=$(virsh pool-info $pool | grep "Capacity" | awk '{print $2}' | sed 's/[^0-9.]//g')
    PERCENT=$(echo "scale=2; $USAGE/$CAPACITY*100" | bc)
    if (( $(echo "$PERCENT > $THRESHOLD" | bc -l) )); then
        echo "WARNING: Pool $pool is ${PERCENT}% full"
    fi
done
EOF

sudo chmod +x /usr/local/bin/storage-alert.sh

🔧 Advanced Pool Management¶

Automated Pool Creation with Ansible¶

Create a comprehensive playbook for pool management:

---
- name: Advanced Storage Pool Management
  hosts: kvm-host
  become: true
  vars:
    storage_configuration:
      pools:
        - name: "ssd-pool"
          type: "dir"
          path: "/var/lib/libvirt/images/ssd"
          performance_tier: "high"
        - name: "archive-pool"
          type: "dir"
          path: "/var/lib/libvirt/images/archive"
          performance_tier: "low"
      policies:
        cleanup_enabled: true
        monitoring_enabled: true
        backup_enabled: true
        
  tasks:
    - name: Create storage directories
      ansible.builtin.file:
        path: "{{ item.path }}"
        state: directory
        mode: '0755'
      loop: "{{ storage_configuration.pools }}"

    - name: Apply performance optimizations
      ansible.builtin.shell: |
        # Apply SSD optimizations
        if [ "{{ item.performance_tier }}" = "high" ]; then
          echo mq-deadline > /sys/block/$(basename $(df {{ item.path }} | tail -1 | awk '{print $1}' | sed 's/[0-9]*$//'))/queue/scheduler
        fi
      loop: "{{ storage_configuration.pools }}"
      when: item.performance_tier is defined

Pool Migration and Backup¶

Backup Pool Configuration¶

# Export pool XML
sudo virsh pool-dumpxml pool-name > pool-name-backup.xml

# Backup pool contents
sudo tar -czf pool-name-backup.tar.gz /var/lib/libvirt/images/pool-name/

Restore Pool Configuration¶

# Restore pool definition
sudo virsh pool-define pool-name-backup.xml

# Restore pool contents
sudo tar -xzf pool-name-backup.tar.gz -C /

# Start restored pool
sudo virsh pool-start pool-name

📋 Storage Pool Policies¶

Implement Storage Quotas¶

# Set filesystem quotas (if supported)
sudo quotacheck -cum /var/lib/libvirt/images
sudo quotaon /var/lib/libvirt/images

# Set user quotas
sudo setquota -u libvirt-qemu 50G 60G 0 0 /var/lib/libvirt/images

Automated Cleanup¶

Create cleanup policies:

# Remove old snapshots
find /var/lib/libvirt/images/ -name "*.snapshot" -mtime +30 -delete

# Clean up temporary files
find /var/lib/libvirt/images/ -name "*.tmp" -mtime +1 -delete

# Archive old VM disks
find /var/lib/libvirt/images/ -name "*.qcow2" -mtime +90 -exec mv {} /var/lib/libvirt/images/archive/ \;

🔍 Troubleshooting¶

Common Storage Issues¶

Problem: “Pool is not active” Solution:

sudo virsh pool-start pool-name
sudo virsh pool-autostart pool-name

Problem: “Permission denied accessing pool” Solution:

sudo chown -R root:root /var/lib/libvirt/images/pool-name
sudo restorecon -R /var/lib/libvirt/images/pool-name

Problem: “Pool out of space” Solution:

# Check usage
df -h /var/lib/libvirt/images/
# Clean up or expand storage
# Move VMs to other pools if needed

📚 Best Practices¶

Pool Organization¶

Separate by purpose: development, staging, production
Separate by performance: SSD pools for databases, HDD for archives
Separate by security: isolated pools for sensitive workloads

Naming Conventions¶

Use descriptive names: prod-db-pool, dev-web-pool
Include performance tier: ssd-high-perf, hdd-archive
Include location if relevant: datacenter1-pool

Capacity Management¶

Monitor usage regularly
Set up automated alerts at 80% capacity
Plan for growth with 20% buffer
Implement automated cleanup policies