Bob Masters Linux Virtualization with KVM on AlmaLinux

Bob’s next challenge was to set up virtual machines (VMs) using KVM (Kernel-based Virtual Machine) on AlmaLinux. Virtualization allows a single physical server to run multiple isolated operating systems, making it a cornerstone of modern IT infrastructure.

“One server, many VMs—time to master virtualization!” Bob said, diving into KVM.

Chapter Outline: “Bob Masters Linux Virtualization with KVM”

1. Introduction: What Is KVM?

   • Overview of virtualization.
   • Why KVM is a powerful choice for Linux.

2. Setting Up KVM on AlmaLinux

   • Installing and configuring KVM and related tools.
   • Verifying hardware virtualization support.

3. Creating and Managing Virtual Machines

   • Using virt-manager for a graphical interface.
   • Managing VMs with virsh.

4. Configuring Networking for VMs

   • Setting up bridged networking.
   • Configuring NAT for VMs.

5. Optimizing VM Performance

   • Allocating resources effectively.
   • Using VirtIO for better disk and network performance.

6. Backing Up and Restoring VMs

   • Snapshot management.
   • Exporting and importing VM configurations.

7. Conclusion: Bob Reflects on Virtualization Mastery

Part 1: Introduction: What Is KVM?

Bob discovered that KVM is a full virtualization solution integrated into the Linux kernel. It turns Linux into a hypervisor, allowing multiple guest operating systems to run on a single machine.

Key Features of KVM

• Open-source and tightly integrated with Linux.
• Supports a wide range of guest operating systems.
• Optimized for performance with VirtIO drivers.

“KVM is powerful, and it’s free—what’s not to love?” Bob said.

Part 2: Setting Up KVM on AlmaLinux

Step 1: Verifying Hardware Virtualization Support

• Check if the CPU supports virtualization:

  lscpu | grep Virtualization
  

• Ensure the virtualization extensions are enabled in the BIOS.

Step 2: Installing KVM and Tools

• Install KVM, qemu, and virtualization tools:

  sudo dnf install -y @virt virt-install qemu-kvm virt-manager libvirt libvirt-client
  

• Enable and start the libvirt daemon:

  sudo systemctl enable libvirtd --now
  

Step 3: Verifying the Installation

• Verify that KVM is active:

  sudo lsmod | grep kvm
  

• Check the virtualization environment:

  sudo virsh list --all
  

“KVM is ready—time to create my first VM!” Bob said.

Part 3: Creating and Managing Virtual Machines

Step 1: Using virt-manager

Bob used the graphical Virtual Machine Manager to create his first VM.

• Launch virt-manager:

  virt-manager
  

• Create a new VM:

  1. Click New Virtual Machine.
  2. Select an ISO file for the guest OS.
  3. Allocate CPU, memory, and disk resources.
  4. Complete the setup and start the VM.

Step 2: Managing VMs with virsh

Bob learned to use the virsh CLI for VM management.

• Create a new VM:

  sudo virt-install \
    --name testvm \
    --vcpus 2 \
    --memory 2048 \
    --disk size=10 \
    --cdrom /path/to/iso \
    --os-variant detect=on
  

• Start and stop VMs:

  sudo virsh start testvm
  sudo virsh shutdown testvm
  

• List all VMs:

  sudo virsh list --all
  

“I can manage VMs with a GUI or CLI—versatility at its best!” Bob noted.

Part 4: Configuring Networking for VMs

Step 1: Setting Up Bridged Networking

• Create a bridge interface:

  sudo nmcli connection add type bridge ifname br0
  

• Attach the physical NIC to the bridge:

  sudo nmcli connection add type bridge-slave ifname enp0s3 master br0
  

• Assign an IP to the bridge:

  sudo nmcli connection modify br0 ipv4.addresses 192.168.1.100/24 ipv4.method manual
  

• Restart the network:

  sudo systemctl restart NetworkManager
  

• Attach the VM to the bridge:

  sudo virsh attach-interface --domain testvm --type bridge --source br0 --model virtio --config
  

Step 2: Configuring NAT for VMs

• Use the default NAT network provided by libvirt:

  sudo virsh net-start default
  sudo virsh net-autostart default
  

Part 5: Optimizing VM Performance

Step 1: Allocating Resources Effectively

• Adjust CPU and memory for a running VM:

  sudo virsh setvcpus testvm 4 --live
  sudo virsh setmem testvm 4096M --live
  

Step 2: Using VirtIO for Improved Performance

Bob configured VirtIO drivers for faster disk and network performance:

• Set the disk interface to VirtIO in virt-manager.
• Use a VirtIO network adapter for faster network throughput.

“With VirtIO, my VMs run smoother than ever!” Bob said.

Part 6: Backing Up and Restoring VMs

Step 1: Managing Snapshots

• Create a snapshot:

  sudo virsh snapshot-create-as --domain testvm snapshot1 --description "Before update"
  

• Revert to a snapshot:

  sudo virsh snapshot-revert --domain testvm snapshot1
  

Step 2: Exporting and Importing VMs

• Export a VM:

  sudo virsh dumpxml testvm > testvm.xml
  sudo tar -czf testvm-backup.tar.gz /var/lib/libvirt/images/testvm.img testvm.xml
  

• Import a VM:

  sudo virsh define testvm.xml
  sudo virsh start testvm
  

“Backups ensure my VMs are safe from accidental changes!” Bob said.

Conclusion: Bob Reflects on Virtualization Mastery

Bob successfully deployed, managed, and optimized virtual machines on AlmaLinux using KVM. With tools like virt-manager and virsh, he could create flexible environments for testing, development, and production.

Next, Bob plans to explore Automating Infrastructure with Ansible on AlmaLinux.