Overview
This lecture explains virtualization concepts, types of hypervisors, resource allocation, networking options, security considerations, virtual desktop infrastructure (VDI), and application containerization.
Virtualization Basics
- Virtualization allows multiple operating systems to run on a single physical system.
- The hypervisor or virtual machine manager handles resource allocation and separation between virtual machines (VMs).
- Hypervisors can use CPU features like Intel VT or AMD-V for improved virtualization performance.
Types of Hypervisors
- Type 1 (bare metal) hypervisor runs directly on hardware without a host operating system (e.g., VMware ESXi, Microsoft HyperV).
- Type 2 (hosted) hypervisor runs on top of an existing operating system (e.g., VMware Workstation, Oracle VirtualBox, Parallels Desktop).
- Both types create VMs that are otherwise functionally identical; the main difference is their position relative to the host OS.
Resource Management
- Each VM requires dedicated CPU cycles, memory, and storage space.
- Ensure sufficient hardware resources are available for simultaneous VM operation.
- Each VM contains its own operating system, applications, and data.
Networking in Virtualization
- Hypervisors control VM network access and can create virtual networks.
- Shared network (NAT): VMs use a separate subnet and communicate externally via network address translation.
- Bridge network: VMs appear as local devices on the same subnet as the host.
- Private network: VMs can be isolated, communicating only with specific devices as configured.
Security Considerations
- Hypervisor security is critical; VM escape is a major threat where malware crosses VM boundaries.
- Each VM should be secured like a standalone machine with firewalls and anti-malware.
- Downloading VMs from untrusted sources may introduce malware; prefer building your own VMs or verifying downloaded images.
Virtual Desktop Infrastructure (VDI)
- VDI or Desktop as a Service (DaaS) runs user desktops as VMs on remote servers or in the cloud.
- Client devices need minimal hardware; processing occurs remotely and is accessed over the network.
- Users interact with VDI as if it were a local OS.
Application Containerization
- Containers virtualize applications without needing a separate OS for each app, unlike VMs.
- Each container is isolated and portable; Docker is a common container platform.
- All containers share a single host OS, simplifying updates but limiting OS diversity across containers.
Key Terms & Definitions
- Hypervisor — software managing VMs and their resource allocation.
- Type 1 Hypervisor — runs directly on hardware (bare metal).
- Type 2 Hypervisor — runs atop a host operating system.
- VM Escape — a security breach allowing malware to jump from one VM to another.
- Virtual Desktop Infrastructure (VDI) — technology running desktops as VMs on remote servers.
- Containerization — running applications in isolated containers sharing a single host OS.
Action Items / Next Steps
- Review the difference between Type 1 and Type 2 hypervisors.
- Assess your system for adequate CPU, RAM, and storage before running multiple VMs.
- Practice creating and securing your own VMs rather than downloading from unknown sources.