Not so long ago, to launch a website or an online service, it was necessary to rent or purchase a whole physical server. This is expensive, difficult to administer, and comes with excessive capacity that often remains unused. The situation changed with the appearance of virtualization — a technology that allows creating several independent virtual servers on a single physical server. Each of them operates as if it has its own processor, memory, disk space, and operating system. The key element of this process is the hypervisor. It acts as a “conductor” that controls the distribution of resources and ensures the stable operation of each VPS.
What a hypervisor is and why it is needed
A hypervisor is a software or hardware-software layer that creates and manages virtual machines. It controls the physical resources of the server and distributes them among several users. The hypervisor guarantees that each VPS receives its portion of computing power and works in isolation from others.
Isolation is a key advantage. If one virtual machine runs under heavy load or, for example, contains software errors, the others should not be affected. The hypervisor strictly controls access to resources, preventing one system from “capturing” memory or processor time belonging to others.
Types of hypervisors: how they work
Usually, two types of hypervisors are distinguished. The first type works directly on the hardware — on the physical server. It loads instead of the usual operating system and has direct control over all components. This approach provides maximum efficiency, speed, and stability. Examples include VMware ESXi, Microsoft Hyper-V, and KVM.
The second type of hypervisor is installed on top of an operating system, that is, it works as an application. It is easier to install but has lower performance, since it must share resources with the base OS. This option is often used for local test environments and home labs.
In most modern data centers, the first type is used for VPS — it allows achieving stable hosting with clear resource allocation and high performance.
How a hypervisor allocates resources
A physical server is a set of resources: processor (CPU), random access memory (RAM), disk space (SSD or NVMe), network interfaces. The hypervisor divides them into parts and “issues” them to each virtual machine.
The processor is allocated as virtual cores (vCPU). A VPS user may receive, for example, 2 cores, but in reality these cores represent part of the capacity of the physical processors of the server. The hypervisor ensures that all virtual cores work fairly, and no machine occupies more than it is supposed to.
Random access memory is allocated within strict limits. If a VPS has 4 GB of RAM, it cannot “enter” the memory of another machine. The hypervisor controls the addressing tables and carefully tracks every byte.
Disk space can be allocated in different ways. In some configurations, a VPS has its own separate partition; in others, it is stored as a disk image file. In data centers that use SSD or NVMe arrays, the hypervisor provides access to high-speed disk input/output, which affects overall performance.
Isolation and security between VPS
One of the main tasks of the hypervisor is to protect virtual machines from each other. Each VPS has its own environment: its own operating system kernel, its own users, its own processes. Two different VPS cannot see each other and cannot access each other’s files or memory.
If one user incorrectly configures a service and it begins to work unstably, other VPS servers remain unaffected. If cyberattacks occur on one VPS, this is also not transferred to others — network interfaces operate in isolation.
In this sense, a VPS works almost like a dedicated physical server, but with optimized use of shared resources.
Overselling: when resources are not enough
Some providers may allocate resources not always honestly. For example, they may sell more virtual cores or RAM than is physically available. This is called overselling. If all users load their VPS at the same time, the server begins to “slow down.” This is a bad practice for professional hosting, so responsible providers allocate resources fairly and monitor the load.
Therefore, the quality of hosting depends not only on the hardware, but also on the provider’s policy and its hypervisor-level resource management.
The hypervisor is the foundation of modern VPS hosting
The hypervisor turns one physical server into several independent environments ready to handle real workloads. It controls resources, ensures isolation, maintains stability, and protects each VPS from the influence of others. Thanks to it, virtual servers have become affordable, flexible, and reliable for businesses of any scale — from small websites to complex corporate systems.
If you choose a VPS, pay attention not only to processor and memory characteristics, but also to which hypervisor is used and what resource allocation policy the provider follows. This directly affects the speed, stability, and security of your server.
Sunny
Virtualization really changed the game, letting you run multiple VPS on one physical server instead of paying for unused capacity. Thanks for the clear, friendly explanation.