Virtual Machines (VM)

Definition

• Software that provides functionality similar to physical computers.
• Runs operating systems and applications on a computer.
• Differs from physical computers as it is a computer file (an image) running on a physical computer using a hypervisor.
• Allows running multiple operating systems on a main OS without additional physical resources.

Characteristics

• Acts like a real computer inside a computer.
• Functions in a window like any program, providing a virtual system experience.
• Sandboxed from the rest of the system to prevent tampering.

Uses

• Ideal for testing operating systems, virus testing, beta releases, running software, and creating backups.
• Multiple VMs can run on one physical computer.

Virtualization

• Hypervisor: Software that manages VMs.
  • Type 1 Hypervisor (Bare Metal): Directly on hardware (e.g., KVM).
  • Type 2 Hypervisor (Hosted): Runs on a host operating system (e.g., VMware Workstation, Oracle VirtualBox).
• Virtual hardware (hard drives, CPUs, network interfaces, memory) mapped to physical hardware.
• Reduces costs, maintenance, and physical hardware requirements.

Configuration

• In VM software like VirtualBox, configure resources for emulated hardware components (e.g., hard drives, RAM, network settings).
• After configuration, install a working system like on a normal computer.

Benefits

• Server Consolidation: Allows multiple VMs on a single physical server, improving hardware usage.
• Minimizes power, space, and cooling needs in data centers.
• Provides failover and redundancy without additional hardware.
• Isolated environments for testing or development.
• Solutions for disaster recovery and implementation.

Disadvantages

• Running multiple VMs can lead to unstable output and less efficiency compared to physical machines.
• VMs can be slower than physical machines.