Virtualization is a key technology in modern IT infrastructure, allowing multiple virtual machines (VMs) to run on a single physical machine. This not only optimizes resource utilization but also provides flexibility, scalability, and isolation.

Introduction to Virtualization

Virtualization is the process of creating a virtual version of something, such as hardware platforms, storage devices, and network resources. It allows multiple operating systems and applications to run on a single physical server, providing improved resource utilization and isolation.

Benefits of Virtualization

  • Resource Optimization: Maximizes the use of physical resources by running multiple VMs.
  • Scalability: Easily scale resources up or down as needed.
  • Isolation: Provides isolated environments for applications, improving security and stability.
  • Flexibility: Allows for easy migration, cloning, and backup of VMs.
  • Cost Savings: Reduces the need for physical hardware, lowering costs.

Types of Virtualization

Full Virtualization

Provides complete abstraction of the underlying hardware, allowing unmodified guest operating systems to run.


Requires modifications to the guest operating system to improve performance by allowing direct access to hardware resources.

Hardware-Assisted Virtualization

Leverages hardware features (e.g., Intel VT-x, AMD-V) to improve virtualization performance and simplify implementation.

Container-Based Virtualization

Uses containerization technologies (e.g., Docker, Kubernetes) to provide lightweight, isolated environments for applications.

Key Virtualization Technologies

KVM (Kernel-based Virtual Machine)

KVM is an open-source virtualization technology built into the Linux kernel. It turns the Linux kernel into a hypervisor, allowing multiple VMs to run on a host.


libvirt is an open-source API, daemon, and management tool for managing platform virtualization. It supports KVM, QEMU, Xen, and other virtualization technologies.


QEMU is an open-source machine emulator and virtualizer. When used with KVM, it provides fast, hardware-assisted virtualization.

oVirt and Red Hat Virtualization

oVirt is an open-source virtualization management platform. Red Hat Virtualization (RHV) is an enterprise virtualization solution based on oVirt, providing advanced management features.

Exercises for Practice:

  1. Setting Up a Virtualization Host:
    • Install and configure KVM on a RHEL system, ensuring proper integration with the Linux kernel.
    • Verify virtualization support using tools like virt-host-validate and dmesg.
  2. Creating and Managing Virtual Machines:
    • Create multiple virtual machines with varying configurations (e.g., CPU, memory, disk size).
    • Experiment with different storage options such as disk images, LVM volumes, and network storage.
  3. Networking and Connectivity:
    • Configure virtual networks and bridges to enable communication between virtual machines and external networks.
    • Test network connectivity and troubleshoot any connectivity issues using tools like ping and traceroute.
  4. Snapshotting and Cloning:
    • Take snapshots of virtual machines at different stages of their lifecycle.
    • Clone existing virtual machines to create duplicates for testing or backup purposes.
  5. Live Migration and High Availability:
    • Perform live migrations of virtual machines between different hosts to minimize downtime.
    • Set up high availability clusters using tools like Pacemaker and simulate failover scenarios.
  6. Security Hardening and Compliance:
    • Implement security measures such as firewall rules, SELinux policies, and user access controls to secure virtualized environments.
    • Conduct compliance audits to ensure adherence to regulatory standards and organizational policies.

By mastering the concepts and practices outlined you can gain the skills and knowledge needed to effectively manage virtualized environments using Red Hat technologies.


Installing and Configuring Virtualization

Setting up KVM and libvirt

Installing KVM and Required Packages

sudo dnf install @virtualization

sudo systemctl enable –now libvirtd

Verifying Installation

lsmod | grep kvm

Managing Virtual Machines with virsh and virt-manager

Creating a New VM with virt-manager

  1. Open virt-manager.
  2. Click Create a new virtual machine.
  3. Follow the wizard to configure the VM.

Managing VMs with virsh

virsh list –all

virsh start <vm-name>

virsh shutdown <vm-name>

virsh create <xml-file>

Networking in Virtualization

Bridged Networking

Allows VMs to appear as individual hosts on the network, sharing the host’s network interface.

Configuring Bridged Networking

  1. Create a bridge interface.
  2. Configure the bridge in the VM’s network settings.

NAT Networking

Provides network address translation for VMs, allowing them to share the host’s IP address.

Configuring NAT Networking

  1. Use virt-manager or virsh to set the network type to NAT.

Host-Only Networking

Isolates VMs from the external network, allowing communication only with the host.

Storage in Virtualization

Storage Pools and Volumes

libvirt manages storage using storage pools (collections of storage volumes) and storage volumes (individual storage units).

Creating a Storage Pool

virsh pool-create-as <pool-name> dir –target /path/to/storage

Creating a Storage Volume

virsh vol-create-as <pool-name> <volume-name> <size>

Network Storage

Use network-based storage (e.g., NFS, iSCSI) to provide scalable and flexible storage solutions for VMs.

Performance Tuning and Optimization

  • CPU Pinning: Assign specific CPU cores to VMs for better performance.
  • Memory Ballooning: Dynamically adjust VM memory usage.
  • IO Tuning: Optimize disk and network IO settings.

Security in Virtualization

SELinux and sVirt

Use SELinux policies and sVirt (Security-Enhanced Virtualization) to isolate VMs and protect against security breaches.

Secure Boot

Ensure that VMs boot securely, preventing unauthorized code execution.

High Availability and Clustering

Implement high availability (HA) and clustering solutions (e.g., RHV, Pacemaker) to ensure continuous VM operation and failover capabilities.

Backup and Recovery

Regularly back up VM images and configurations to ensure quick recovery in case of failure.

Backup Tools

  • virsh dump: Create a backup of a running VM.
  • snapshot-create-as: Create VM snapshots.

Troubleshooting Virtualization Issues

  • Log Files: Check /var/log/libvirt and VM-specific logs.
  • virsh Commands: Use virsh to diagnose and fix issues.
  • Network Issues: Verify network configurations and connectivity.

Best Practices

  • Regularly update virtualization software.
  • Monitor VM performance and resource usage.
  • Implement strong security measures, including firewalls and SELinux.
  • Plan and document VM configurations and policies.

By mastering these topics, you will be capable of effectively managing and optimizing virtualization in a Red Hat environment.

Revision: Virtualization

  1. Start/Stop libvirtd Service:

systemctl start libvirtd

systemctl stop libvirtd

Example: Start the libvirtd service:

systemctl start libvirtd

  1. Enable libvirtd Service on Boot:

systemctl enable libvirtd

Example: Enable the libvirtd service to start on boot:

systemctl enable libvirtd

  1. Check Status of libvirtd Service:

systemctl status libvirtd

Example: Check the status of the libvirtd service:

systemctl status libvirtd

  1. List Available Virtual Machines:

virsh list –all

Example: List all available virtual machines:

virsh list –all

  1. Start/Stop Virtual Machine:

virsh start <vm_name>

virsh shutdown <vm_name>

Example: Start a virtual machine named “myvm”:

virsh start myvm

  1. Create Virtual Machine:

virt-install –name <vm_name> –memory <memory_size> –vcpus <num_of_vcpus> –disk <disk_path> –network network=default –graphics=none –console pty,target_type=serial –location <iso_file>

Example: Create a virtual machine named “newvm” with 2GB memory, 2 vCPUs, and using an ISO file for installation:

virt-install –name newvm –memory 2048 –vcpus 2 –disk /var/lib/libvirt/images/newvm.qcow2 –network network=default –graphics=none –console pty,target_type=serial –location /path/to/os.iso

  1. Delete Virtual Machine:

virsh undefine <vm_name>

Example: Delete a virtual machine named “oldvm”:

virsh undefine oldvm

  1. Set Virtual Machine Autostart:

virsh autostart <vm_name>

Example: Set a virtual machine named “importantvm” to autostart on boot:

virsh autostart importantvm

These examples demonstrate how to perform various virtualization tasks using commands.

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