Physical Servers vs Virtual Machines vs Containers What’s the Difference?
What is a physical server?
The physical server vs virtual server comparison should start with the definition. A physical server, also known as a ‘bare-metal server,’ is a single-tenant computer server, meaning that a specific physical server is designated to a single user. The resources and components of a physical server are not shared between multiple users. Each physical server includes memory, processor, network connection, hard drive, and an operating system (OS) for running programs and applications. A bare-metal server is large in size due to the powerful processing components that it contains.
What is a virtual machine?
A virtual machine (VM) is a software computer used as an emulation of an actual physical computer. A virtual server operates in a “multi-tenant” environment, meaning that multiple VMs run on the same physical hardware. In this case, the computing resources of a physical server are virtualized and shared among all VMs running on it. The architecture of a virtual server is a little more complex than that of a physical server. Thus, a hypervisor, such as VMware vSphere or Microsoft Hyper-V, is installed on top of physical hardware. A hypervisor is then used to create and manage VMs, which have their own virtual computing resources. After that, you can load multiple guest OSes and server applications on top of the virtual hardware. Thus, virtual servers allow you to run several OSes and applications on the basis of the shared physical hardware, which makes it a more cost-effective option than a physical server.
What is a container?
Operating system (OS) virtualization has grown in popularity over the last decade to enable software to run predictably and well when moved from one server environment to another. But containers provide a way to run these isolated systems on a single server or host OS.
Containers sit on top of a physical server and its host OS—for example, Linux or Windows. Each container shares the host OS kernel and, usually, the binaries and libraries, too. Shared components are read-only. Containers are thus exceptionally “light”—they are only megabytes in size and take just seconds to start, versus gigabytes and minutes for a VM.
Containers also reduce management overhead. Because they share a common operating system, only a single operating system needs care and feeding for bug fixes, patches, and so on. This concept is similar to what we experience with hypervisor hosts: fewer management points but slightly higher fault domain. In short, containers are lighter weight and more portable than VMs.
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