Scalable and flexible virtual machines

What is a virtual machine (VM)?

A virtual machine (VM) is a software-based emulation of a physical computer that runs on a host system. VMs provide an isolated environment where operating systems (OS) and applications can run independently of the underlying hardware. VMs enable multiple instances of operating systems to coexist and share resources on a single physical machine, increasing resource utilization and flexibility.

How do virtual machines work?

Virtual machines work using a hypervisor, a layer of software that sits between the host hardware and guest operating system. The hypervisor is responsible for emulating the underlying hardware, allocating resources, and managing the isolation between VMs. There are two types of hypervisors:

• Type 1 (Bare-metal hypervisors): These hypervisors run directly on the hardware and have complete control over the underlying physical resources.
• Type 2 (Hosted hypervisors): These hypervisors run on top of an existing host OS and use the host’s hardware resources to create VMs. DigitalOcean offers hosted Linux hypervisors.

What are virtual machines used for?

Virtual machines have numerous use cases, including:

• Server consolidation: By running multiple virtual machines on a single physical server, organizations can reduce hardware costs, improve resource utilization, and simplify management.
• Software development and testing: Developers can create, test, and deploy applications within isolated environments without affecting the host system or other VMs.
• Legacy software support: Virtual machines enable the use of outdated OS and applications, allowing businesses to maintain legacy systems while upgrading their infrastructure.
• Cloud computing: Cloud providers like DigitalOcean use virtual machines to provide scalable, on-demand computing resources to customers (cloud environments). These enable rapid deployment and flexible resource allocation.

What are the 5 types of virtual machines?

The five types of virtual machines are:

1. System VMs: These VMs provide a complete system platform, emulating an entire physical machine, including CPU, memory, storage, and network devices.
2. Process VMs: These virtual machines provide an isolated environment for executing individual processes or applications, abstracting the physical servers and operating systems.
3. Para-virtualized VMs: These virtual machines run on a modified OS, designed to communicate directly with the hypervisor, improving performance and resource utilization.
4. Hardware-assisted VMs: These utilize specialized hardware features to enhance virtualization performance and security.
5. Nested VMs: These VMs run within another VM, allowing for multi-level virtualization.**

What are the benefits of using VMs?

The main benefits of using VMs include:

• Resource optimization: Virtual machines enable better resource utilization by consolidating multiple workloads onto a single physical machine.
• Isolation: Virtual machines provide isolated environments, ensuring that issues in one VM do not impact other VMs or the host computer.
• Flexibility: VMs can be easily created, modified, or deleted, allowing for rapid deployment and scaling.
• Migration and recovery: Virtual machines can be quickly migrated between physical machines, facilitating disaster recovery and load balancing.

What are the drawbacks of using VMs?

The drawbacks of using virtual machines include:

• Performance overhead: Virtual machines introduce performance overhead due to the additional layer of software virtualization.
• Licensing costs: Running multiple instances of OS and applications may require additional licensing fees.
• Complexity: Managing VMs can be complex, requiring specialized knowledge and tools.

Containers vs. virtual machines

Containers and virtual machines both provide isolated environments for running applications, but they differ in their implementation and resource usage. Containers share the host OS kernel, reducing overhead and allowing for faster startup times, while VMs run a full OS stack, providing better isolation and flexibility. Here’s a comparison:

• Resource utilization: Containerization generally has lower resource overhead than VMs, as it shares the host operating system kernel and require less memory and storage.
• Startup time: Containers have faster startup times, as they do not need to boot an entire OS.
• Isolation: VMs provide stronger isolation between instances, as they run separate OS instances. Containers share the host OS kernel, which can potentially lead to security risks.
• Compatibility: Virtual machines can run different OS instances on the same host, while containers are limited by the host operating system kernel.
• Management: Container orchestration platforms like Kubernetes have simplified container management, while VM management often requires specialized tools and expertise.

Choosing between containers and VMs depends on the specific requirements of the application, the desired level of isolation, and the available infrastructure. In some cases, a hybrid approach using both containers and VMs may be the most suitable solution.

What is a Droplet?

DigitalOcean Droplets are Linux-based virtual machines that run on top of virtualized hardware. Each Droplet you create is a new server you can use, either standalone or as part of a larger, cloud-based infrastructure.

Which Droplet should I choose?

Choosing the right Droplet plan depends on your workload. Please refer to this article that explains the differences between shared and dedicated CPUs, and goes into detail on each Droplet plan.

What operating systems do DigitalOcean VMs support?

DigitalOcean VMs run Linux operating systems. Choose from popular OS’s including Ubuntu, CentoS, and Debian. We also support uploading guest operating systems and virtual appliances using our custom images feature.