Storage Pool Creation

This tutorial teaches you how to create and manage storage pools for your virtual machines. Storage pools are essential for organizing and managing VM disk images efficiently.

🎯 What You’ll Learn

In this tutorial, you will:

• Understand different storage pool types

• Create directory-based storage pools

• Set up LVM-based storage pools

• Configure storage pool permissions

• Create your first VM disk image

• Understand storage best practices

📋 Prerequisites

Before starting this tutorial:

• Complete Your First KVM Host Setup

• Complete Basic Network Configuration

• Have a working KVM host with libvirt configured

• Understand basic storage concepts (directories, LVM, disk space)

💾 Understanding Storage Pool Types

Directory Pools

• Store VM disks as files in a directory

• Simple to set up and manage

• Good for: Development, small deployments

• Location: Usually /var/lib/libvirt/images

LVM Pools

• Use LVM logical volumes for VM storage

• Better performance and management

• Good for: Production, large deployments

• Requires: LVM volume group

Network Storage Pools

• Use network-attached storage (NFS, iSCSI)

• Shared storage across multiple hosts

• Good for: Clustered environments, migration

🚀 Step 1: Check Current Storage

First, let’s examine your current storage configuration:

# List existing storage pools
sudo virsh pool-list --all

# Check default pool details
sudo virsh pool-info default
sudo virsh pool-dumpxml default

# Check available disk space
df -h /var/lib/libvirt/images

📝 Step 2: Create Additional Directory Pool

Let’s create a dedicated storage pool for development VMs:

Create configure-storage-pools.yml:

---
- name: Configure Storage Pools
  hosts: kvm-host
  become: true
  vars:
    storage_pools:
      - name: "development"
        type: "dir"
        path: "/var/lib/libvirt/images/development"
        owner: "root"
        group: "root"
        mode: "0755"
      - name: "production"
        type: "dir"
        path: "/var/lib/libvirt/images/production"
        owner: "root"
        group: "root"
        mode: "0755"
        
  tasks:
    - name: Create storage directories
      ansible.builtin.file:
        path: "{{ item.path }}"
        state: directory
        owner: "{{ item.owner }}"
        group: "{{ item.group }}"
        mode: "{{ item.mode }}"
      loop: "{{ storage_pools }}"
      when: item.type == "dir"

    - name: Create storage pool XML definitions
      ansible.builtin.template:
        src: dir-pool.xml.j2
        dest: "/tmp/{{ item.name }}-pool.xml"
      loop: "{{ storage_pools }}"
      when: item.type == "dir"

    - name: Define storage pools
      community.libvirt.virt_pool:
        command: define
        name: "{{ item.name }}"
        xml: "{{ lookup('file', '/tmp/' + item.name + '-pool.xml') }}"
      loop: "{{ storage_pools }}"
      when: item.type == "dir"

    - name: Start and autostart storage pools
      community.libvirt.virt_pool:
        name: "{{ item.name }}"
        state: active
        autostart: true
      loop: "{{ storage_pools }}"

Create the storage pool template templates/dir-pool.xml.j2:

<pool type="dir">
  <name>{{ pool_name }}</name>
  <target>
    <path>{{ pool_path }}</path>
    <permissions>
      <mode>{{ pool_mode }}</mode>
      <owner>{{ pool_owner }}</owner>
      <group>{{ pool_group }}</group>
    </permissions>
  </target>
</pool>

⚙️ Step 3: Set Up LVM Storage Pool (Optional)

If you want better performance and management, create an LVM-based pool:

First, check if you have available space for LVM:

# Check available disk space
sudo vgdisplay
sudo pvdisplay
sudo lsblk

If you have a spare disk or partition, add LVM configuration to your vars:

    lvm_storage:
      - name: "vm-storage"
        vg_name: "vg_vms"
        device: "/dev/sdb"  # Replace with your available device
        size: "50G"

Add LVM tasks to your playbook:

    - name: Create LVM volume group for VMs
      community.general.lvg:
        vg: "{{ item.vg_name }}"
        pvs: "{{ item.device }}"
      loop: "{{ lvm_storage | default([]) }}"
      when: lvm_storage is defined

    - name: Create LVM storage pool XML
      ansible.builtin.template:
        src: lvm-pool.xml.j2
        dest: "/tmp/{{ item.name }}-lvm-pool.xml"
      loop: "{{ lvm_storage | default([]) }}"
      when: lvm_storage is defined

🔧 Step 4: Run Storage Configuration

Execute your storage configuration:

ansible-playbook -i inventory.yml configure-storage-pools.yml

✅ Step 5: Verify Storage Pools

Check that your storage pools were created:

# List all storage pools
sudo virsh pool-list --all

# Check pool details
sudo virsh pool-info development
sudo virsh pool-info production

# Verify pool paths
ls -la /var/lib/libvirt/images/

💿 Step 6: Create Your First VM Disk

Now let’s create a disk image in one of your new pools:

# Create a 20GB disk in the development pool
sudo virsh vol-create-as development test-vm-disk.qcow2 20G --format qcow2

# List volumes in the pool
sudo virsh vol-list development

# Check disk details
sudo virsh vol-info test-vm-disk.qcow2 development

🔒 Step 7: Set Up Storage Permissions

Ensure proper permissions for libvirt access:

# Set SELinux contexts (if SELinux is enabled)
sudo setsebool -P virt_use_nfs 1
sudo restorecon -R /var/lib/libvirt/images/

# Verify permissions
ls -laZ /var/lib/libvirt/images/

🧪 Step 8: Test Storage Performance

Basic performance test of your storage:

# Test write performance
sudo dd if=/dev/zero of=/var/lib/libvirt/images/development/test-file bs=1M count=1000 conv=fdatasync

# Test read performance
sudo dd if=/var/lib/libvirt/images/development/test-file of=/dev/null bs=1M

# Clean up test file
sudo rm /var/lib/libvirt/images/development/test-file

🎉 What You’ve Accomplished

Excellent! You now have:

• ✅ Multiple storage pools for different purposes

• ✅ Understanding of directory vs LVM storage

• ✅ Proper permissions and security contexts

• ✅ Your first VM disk image

• ✅ Knowledge of storage performance testing

• ✅ Organized storage structure for VMs

💡 Storage Best Practices

Pool Organization

• development: For testing and development VMs

• production: For production workloads

• templates: For VM templates and base images

• backups: For VM backups and snapshots

Naming Conventions

• Use descriptive pool names

• Include environment in disk names: dev-webserver.qcow2

• Use consistent file extensions: .qcow2 for QEMU images

Performance Tips

• Use LVM for better performance in production

• Consider SSD storage for database VMs

• Monitor disk space regularly

• Use thin provisioning when appropriate

🔄 Next Steps

With storage configured, you can:

1. Create your first VM - Use your new storage pools

2. Explore advanced storage - Check How-To Guides

3. Set up automated backups - See Configure Backup Automation

4. Learn about VM templates - Try Deploy VMs from Templates

🆘 Troubleshooting

Common Issues

Problem: “Permission denied creating storage pool” Solution: Check directory permissions and SELinux contexts

Problem: “LVM volume group not found” Solution: Verify the device exists and isn’t already in use: sudo pvdisplay

Problem: “Storage pool already exists” Solution: Use sudo virsh pool-undefine POOL_NAME to remove existing pools

Storage Monitoring

Monitor your storage usage:

# Check pool capacity
sudo virsh pool-info POOL_NAME

# Monitor disk usage
df -h /var/lib/libvirt/images/

# Check for thin provisioning
sudo qemu-img info /path/to/disk.qcow2

🔗 Related Documentation

• Previous: Basic Network Configuration

• Next: Multi-Host KVM Environment

• Advanced: Manage Storage Pools

• Reference: Storage Variables

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This tutorial covered fundamental storage concepts. For production storage strategies and advanced configurations, explore our How-To Guides and Reference documentation.