Virtual machine (VM)

Definition

A virtual machine (VM) is a software-based emulation of a physical computer that runs an operating system and applications just like a real machine. It utilizes virtualization technologies to abstract hardware resources, enabling multiple VMs to operate on a single physical host, thereby maximizing resource utilization and flexibility.

5 Must Know Facts For Your Next Test

1. Virtual machines allow users to run multiple operating systems on a single physical server, facilitating development, testing, and production environments.
2. Each VM operates in its own isolated environment, meaning it can be rebooted or modified without affecting other VMs on the same host.
3. Resource allocation for VMs can be dynamically adjusted, allowing administrators to allocate CPU, memory, and storage based on demand.
4. VMs enhance security by isolating applications from one another; if one VM is compromised, others on the same host remain unaffected.
5. The performance of VMs may be impacted by the overhead introduced by virtualization layers, but advancements in hardware support have significantly reduced this gap.

Review Questions

• How do virtual machines improve resource utilization in a physical server environment?
  • Virtual machines improve resource utilization by allowing multiple VMs to run concurrently on a single physical server. Each VM can independently run different operating systems and applications while sharing the physical hardware resources. This efficient use of resources not only maximizes the capabilities of the physical server but also reduces costs associated with hardware acquisition and maintenance.
• Discuss the role of hypervisors in managing virtual machines and how they contribute to virtualization technologies.
  • Hypervisors play a critical role in managing virtual machines by acting as an intermediary between the physical hardware and the VMs. They allocate resources such as CPU, memory, and storage to each VM while ensuring isolation between them. There are two types of hypervisors: Type 1 runs directly on the hardware (bare-metal), while Type 2 runs on top of an existing operating system. This architecture allows for efficient utilization of server resources and simplifies the management of multiple VMs.
• Evaluate the impact of virtual machines on security in computing environments and discuss potential vulnerabilities.
  • Virtual machines can significantly enhance security in computing environments by providing isolation between different workloads. If one VM is compromised, it does not directly impact other VMs on the same host. However, potential vulnerabilities still exist; for instance, flaws in hypervisors can lead to attacks that cross VM boundaries. Additionally, proper configuration and management are crucial to prevent issues such as resource exhaustion or unauthorized access. As virtualization continues to evolve, addressing these vulnerabilities becomes increasingly important for maintaining secure environments.

Related terms

Hypervisor: A hypervisor is a software layer that enables the creation and management of virtual machines by controlling the underlying physical hardware.

Containerization:

Containerization is a lightweight form of virtualization that allows applications to run in isolated environments called containers, sharing the same operating system kernel.

Snapshot: A snapshot is a point-in-time copy of a VM's state, including its disk, memory, and settings, which can be used for backup or recovery purposes.