Key Takeaways
- Virtual Private Server, or VPS solutions, are at the forefront of cloud computing.
- Cloud computing services utilize virtualization to expand a single server into numerous virtual machines.
- OpenVZ and KVM are among the most popular implementations of virtualization technology.
- The major difference between KVM and OpenVZ is how they implement virtualization.
- OpenVZ is an OS-level virtualization software that divides a single Linux host kernel into various containers.
- KVM utilizes hypervisor technology to achieve full virtualization, allowing the creation of isolated virtual machines with OS flexibility.
- OpenVZ is budget-friendly and can run on old hardware without much issue.
- KVM servers require newer hardware and are expensive to run due to performance overhead costs.
- OpenVZ boasts standard Linus isolation and access control but is less robust than the full isolation offered by KVM.
- OpenVZ is best for small businesses prioritizing consistent operation and performance on a budget without requiring complete isolation.
- KVM is ideal for businesses wanting a secure, isolated virtual environment with flexibility and higher customizability.
Virtual Private Servers (VPS) lie at the core of modern cloud computing. Cloud servers are server clusters hosting hundreds if not thousands of virtual machines, all using the same hardware yet completely isolated and secure from each other. OpenVZ and KVM are the leading players in the world of VPS technology. Both these are opening new doors to cloud computing.
OpenVZ vs KVM is a prominent debate in the VPS space. Both technologies offer robust, well-tested, trustworthy virtualization with unique quirks and features. Choosing between OpenVZ and KVM can be challenging, as both are industry leaders in VPS creation.
In this blog, we will analyze the OpenVZ vs KVM debate and present a concise breakdown of the technologies. This should prove useful to anyone mulling over the choice or curious to learn more about the two. Let’s dive into the virtual world of OpenVZ vs KVM and see what we can find!
Table of Contents
- Key Takeaways
- What Is OpenVZ?
- What is KVM?
- Comparing OpenVZ vs KVM – A Quick Guide to VPS Hosting
- Conclusion
- FAQs
What Is OpenVZ?
Image Credit: OpenVZ
OpenVZ is an open-source virtualization solution based on the Linux kernel. OpenVZ utilizes Operating System (OS) level virtualization to split a single Linux kernel into multiple containers. Each container is separate and isolated from the rest and is assigned a portion of the server’s physical resources.
OpenVZ deviates from traditional hypervisor-powered virtualization, instead segmenting the operating system into different machines.
Key Features of OpenVZ Virtualization
We have compiled a list of key features offered by OpenVZ with brief explanations to help understand how the technology works:
Two-Level Disk Quota
OpenVZ comes equipped with fine-grain disk space management. The two-level disk quota system allows administrators to micro-manage and fine-tune disk space use. The two-level quota system is a genius way to allocate space, as it offers space management at the container and user levels. Admins can set containers to have fixed disk space quotas, and further divide those quotas among individual users.
For example, consider a server divided into two containers using OpenVZ. Each container is allotted 50% of the disk space and has two unique user profiles. The two-level disk quota lets you set up the initial 50% quota and then also set individual quotas for the user. So, in this case, the container’s 50% resources can be further split between the users.
I/O Scheduler
The Input/Output or I/O scheduler is a useful tool in OpenVZ that ensures the fair distribution of disk input/output operations between containers. It prevents conflicting I/O operations and disk access monopolization by a single container.
Data Checkpoints and Live Migration
Data Checkpoints and live migration are advanced safety features packaged with OpenVZ. These features allow users to snapshot and create checkpoints of the container as if it were a video game. These checkpoints can then be loaded and live migrated to a different physical server so operations can continue without disruption or downtime in the VPS.
Fair CPU Scheduler
As the name suggests, the fair CPU scheduler ensures fair use of the physical server’s CPU processing power. Since the same hardware is used to power multiple virtual servers, processing power is split between them. The fair scheduler allocates certain portions of CPU resources to each container per their needs. It also ensures no container monopolizes CPU resources and hinders neighbor VPS operations.
User Beancounters
User Beancounters are a resource management feature in OpenVZ that tracks and limits various resources consumed by each container. It is a monitoring tool that helps admins keep up with resource usage and enforce limits or divert additional resources depending on the situation
What is KVM?
Image Credit: KVM
KVM stands for Kernel-based Virtual Machine and is part of the standard Linux distribution. KVM utilizes traditional type 1 hypervisor technology to create multiple virtual machines on the same physical server. Since KVM utilizes a hypervisor, the created VMs are not bound to the Linux OS and can run Windows or BSD as guest operating systems.
Also Read: How to Install KVM on Ubuntu 20.04
Key Features of KVM Virtualization
KVM is an iconic part of Linux today, with some standout features that make it a popular choice for VPS setup:
KVM Paravirtual Clock
The KVM paravirtual clock is a time synchronization system that syncs the clock of VMs with the host. When hypervisor technology is in use, device clocks can end up desynced from the host and cause issues with task scheduling. The paravirtual clock syncs the VM OS clock with the host Linux clock and regularly resyncs it to ensure minimal time drifting and boost clock accuracy.
VMChannel
VMChannel is a communication mechanism packaged with KVM. It allows VM users to communicate with the server host. Simple data exchanges and tasks that require quick, low-latency communications are managed via VMChannel.
QEMU Monitor Protocol (QMP)
Quick Emulator, or QEMU, is an open-source hardware emulation software often used alongside KVM. QEMU emulates hardware in virtual machines to deliver near-native performance. It utilizes hardware-assisted virtualization features like Intel VT-x and AMD-V to maximize efficiency.
QMP is a JSON protocol used with KVM to manage QEMU instances. Put simply, QMP gives users heightened control over their VM and enhanced control over hardware and software virtualization interaction. QMP is also integral for automation and external feature integration.
Nested Guests
KVM comes with the ability to create VMs within VMs. It sounds confusing but is much more straightforward than it sounds. New VMs can be created within an existing VM using the nested guest feature. Imagine a VM hosted directly on the physical server. The VM owner can use KVM to set up a nested guest operating system within the VM.
This is a useful feature when you need access to isolated environments for testing purposes. Developers use nested guests to create custom-testing VMs within a VM for efficient resource use. Using nested guests does introduce performance overhead as more resources are needed to fuel multiple nested VMs.
Virtual CPU / PCI Hotplug Support
Hotplug support is an advanced feature that allows technicians and admins to modify virtual CPU and PCI components without going offline. This feature adds a lot of flexibility to a VPS, allowing for resources to be added or removed without downtime, depending on workload.
Comparing OpenVZ vs KVM – A Quick Guide to VPS Hosting
Let’s dive headfirst into the OpenVZ vs KVM debate and learn how these solutions solve problems in their own unique ways:
Hardware Requirements
Below is a breakdown of the hardware requirements for running OpenVZ vs KVM:
Memory Usage
Since OpenVZ utilizes containers on a single operating system, memory usage is far more efficient. KVM runs separate operating systems on every VM, each needing dedicated memory. This makes the overall memory requirements much higher for KVM, impacting efficiency.
Performance
KVM’s use of hardware-assisted virtualization delivers near-native performance, but running multiple operating systems takes its toll on the system. Resources are required to run multiple VMs concurrently, none of which go towards actually powering the VMs. Imagine CPU and memory being consumed just to maintain the VMs, with more needed for the actual VM operations.
OpenVZ is excellent for low latency high-speed usage. The single-host OS structure minimizes performance overhead, maximizing efficiency while delivering consistent performance. OpenVZ vs KVM performance is very similar, with higher performance leading to higher costs and heavier setups.
Must Read: Basic Knowledge to Get You Started with VPS Hosting
Kernel OS Support
Speaking of OS flexibility, this is a key metric for decision-making. Some business software, applications, and custom technologies need specific OS support. OpenVZ is restricted to Linux operating systems and has no access to Windows or BSD.
KVM, meanwhile, supports most operating systems and allows them to be hosted as guests in VMs. This is a major point in favor of KVM, as businesses value flexibility very highly in the current ever-changing landscape.
Security
KVM VPS is the king when it comes to secure virtualization. Because of the hypervisor separation, every VM is assigned a unique IP address and an isolated and access-controlled OS. Nobody from a neighboring VM can breach your VM in this case. Businesses needing heightened data security must invest in KVM to ensure no data leaks.
OpenVZ is far more lax on security as the containers share common memory and disk space. Hackers can easily breach one container on the physical server and compromise all other containers thanks to there being one host kernel. Beyond standard Linux security features and access control, OpenVZ lacks extra security and complete isolation. OpenVZ containers still share resources, which could be exploited in a security breach. These need to be integrated with additional external tools like SELinux.
OpenVZ is optimal for cases where security is not paramount and what matters more is a working, affordable server.
Cost
KVM and OpenVZ are open-source software, meaning they are free to use. This does not mean that they are free to run, and the costs we are discussing relate to what is required to support VPSs built on these solutions.
It costs significantly more to run a KVM-based VPS, as every VM needs dedicated resources. The performance overhead can drastically increase power consumption and thermal management costs. OpenVZ-based VPSs are much more efficient and lighter on the pockets of data center owners.
Conclusion
Comparing the two, it becomes a matter of priority. Would you be willing to spend more to sustain KVM-based virtualization for enhanced isolation and OS flexibility? Or would you rather achieve amazing, cheaper performance gains at the cost of being restricted to the Linux ecosystem and having worse isolation? Whatever your answer to these questions is will be a key factor in deciding between OpenVZ and KVM.
In all this chatter about virtualization, we cannot forget that the hardware is just as important. Choosing robust hardware from trusted vendors for hosting your VPS is as relevant as the OpenVZ vs KVM choice. RedSwitches offers some of the best bare metal server hosting options for businesses, with cutting-edge hardware that can support even the most demanding VPS setups.
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FAQs
Q. What is the major difference between OpenVZ VPS and KVM?
OpenVZ utilizes OS-based virtualization to create containers within the Linux kernel. KVM is a full virtualization solution that leverages hardware-assisted virtualization to run isolated VMs, each capable of running different operating systems.
Q. Which virtualization technology is more efficient in terms of resource usage?
OpenVZ uses a shared kernel, which leads to lower memory and CPU overhead than KVM, which requires separate OS instances for each VM.
Q. Which performs better for I/O-intensive applications, OpenVZ or KVM?
OpenVZ often performs better for I/O-intensive applications due to its lower overhead and direct use of the host’s kernel.
Q. How does the scalability of OpenVZ compare to KVM?
OpenVZ scales better regarding the number of containers that can run on a single host, as containers are more lightweight than full VMs managed by KVM.
Q. What is the difference between OpenVZ and KVM in terms of isolation?
KVM allows for more robust isolation due to separated kernel utilization. One compromised VM on a KVM-based VPS will not result in the whole server being breached. This is a much bigger risk with OpenVZ, as all containers use the same host kernel.
Q. Are OpenVZ containers secure enough for multi-tenant environments?
OpenVZ offers a secure environment for multi-tenant environments with proper configuration and regular updates. KVM offers stronger isolation and may be preferred for high-security requirements.
Q. Can OpenVZ run different operating systems like Windows?
OpenVZ is limited to Linux-based operating systems due to its shared kernel model. KVM is more versatile. KVM can run various operating systems, including Linux, Windows, and others.
Q. Which is better for dedicated server hosting providers, KVM vs OpenVZ VPS?
OpenVZ is often better for hosting providers looking to maximize server density and efficiency for Linux-based services. Providers needing a wider range of OS options and stronger isolation run KVM.
Q. Is OpenVZ suitable for development and testing environments?
OpenVZ systems are suitable for development and testing, especially for Linux-based applications that benefit from efficient resource usage and quick container creation.
Q. What is the difference between KVM and OpenVZ regarding maintenance?
OpenVZ allows for easier maintenance due to lower overhead demand by OpenVZ servers. KVM requires regular updates and maintenance of individual VMs, including operating systems and applications.
