Server virtualization has been with us since the rapid rise of VMware almost two decades ago. With server sprawl so prevalent in the days when there were endless Windows boxes strewn across the data center or server room, it made perfect sense to consolidate multiple physical servers into one physical machine containing many virtual machines (VMs). This immediately boosted that bane of IT in the early 2000s — poor rates of server utilization due to the model of one physical server hosting one application.
Server virtualization, then, is the process of dividing a physical server into many virtual servers. It is accomplished via software that enables each VM to run its own operating systems independently within a virtualization layer.
While VMware was the early pioneer, it doesn’t have it all its own way. Virtualization platforms from Microsoft, Red Hat, Citrix, and others make this a hot area of competition. Vendors continually update their offerings with features that improve networking performance, incorporate containers, or provide greater cloud functionality, to cite a few examples.
Benefits of Server Virtualization
Server virtualization has many benefits. As a result, IT adopts it due to a variety of use cases. These include:
- Server utilization. Typical physical server utilization can be as low as 10%. In consolidating multiple workloads by virtualizing the server, utilization levels can be increased by as much as 80%, affording significant cost savings.
- Simplified maintenance. Having fewer servers immediately means that IT’s maintenance burden is reduced.
- Greater control of assets. Virtualization makes it much easier to provision VMs, distribute patches, monitor performance, and a host of other tasks.
- Centralizing and consolidating management of workloads. Virtualization arms IT with the ability to monitor workloads, rapidly redistribute tasks to VMs and CPUs based on performance metrics, and direct workloads more evenly across the organization.
- Security. By virtualizing servers, data is better safeguarded from malware and ransomware through simplified backup, restore, and snapshot capabilities.
- Network management. The hypervisor keeps track of the networks that a VM needs to connect to, whether they are different physical networks or VLANs. This ensures that network access is established when a VM is started, no matter which host it starts on. For example, you can query hypervisors to identify what networks specific VMs are using and what the associated MAC is, making life easier for the network administrator. Further, it is easier to move a VM to another network or add additional virtual NICs.
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Server Virtualization Software Selection
Those in the process of selecting server virtualization software, should pay attention to several key areas.
Operating System Support
Obviously, any virtualization platform should support whatever operating systems (OS) are in use in the organization. Note, though, that some server virtualization varieties are more suited to a specific OS, while others are agnostic.
Some organizations are committed to vendors such as Microsoft, VMware, Oracle, IBM, or Citrix. In those cases, it doesn’t usually make sense to choose a hypervisor that goes against the grain. Those settled on Microsoft, for example, should probably stick to Hyper-V. Similarly, those heavily invested in the open source world, should probably stick to open source platforms such as Red Hat or Proxmox.
Some virtualization platforms scale better than others. If scalability is important, it may be wise to pay more for a platform that provides greater scalability features and offers the underlying infrastructure to deal with a huge number of VM. Further, scalability can work both ways. Some platforms do a better job than others of ramping up and down VM numbers due to seasonal demands and other factors.
Some virtualization software is more memory intensive than others. Therefore, simplicity or complexity of the virtualization environment must be considered. For basic needs, opt for a solution that saves headroom mainly for VMs without loading up the platform with a host of unnecessary bells and whistles. But others need those advanced features and so should opt for more sophisticated platforms that demand more in terms of memory and CPU power.
Also read: Transforming Networks: From Virtualization to Cloudification
Top Virtualization Software
There are many choices out there for server virtualization software. Here are our top picks in no particular order:
- Citrix Hypervisor
- Red Hat Virtualization
- VMware vSphere
- Proxmox VE
- Microsoft Hyper V
- Nutanix AHV
- Oracle PowerVM
- IBM VM VirtualBox
Citrix Hypervisor includes optimization for workloads running on Citrix Virtual Apps and Desktops. With tight feature integration throughout the stack, Citrix Hypervisor exposes hardware-level features to boost the user experience, improve security, and simplify operational and network management. Containing plenty of enterprise features, Citrix Hypervisor can handle different workload types, mixed operating systems, and complex storage or networking requirements. Citrix is probably a good choice for those organizations deploying other Citrix tools.
- Enterprise-grade feature set
- Simplified management across networks and virtualization environments
- Moves GPU-accelerated VMs between hosts with NVIDIA vGPU live migration to make graphical workloads more agile.
- Hypervisor Introspection (developed in conjunction with Bitdefender) can reduce the attack surface that can come from legacy, unprotected, or misconfigured browsers and careless browsing activity.
- Support for PVS-Accelerator, which enhances boot performance in Citrix deployments by providing a cache to improve VM boot storm performance and reduce network utilization.
- Licensed on a per-socket basis rather than per-core.
Red Hat Virtualization
Red Hat Virtualization is an infrastructure solution for virtualized servers and technical workstations. Built on the Red Hat Enterprise Linux platform and KVM (Kernel-based Virtual Machine), it provides ease of use, agility, and security for virtualized, resource-intensive workloads. It helps organizations optimize their IT infrastructure with better performance, competitive pricing, and a Red Hat environment. This platform works best for existing Red Hat customers or those favoring open source.
- Lower total cost of ownership (TCO) as the software is open source. Users pay for the service and support from Red Hat.
- Improved security: The code is backed by a team of engineers who monitor, identify, and address risks to protect data from security concerns.
- No vendor lock-in as open source software is employed.
- High performance.
- Support cases are routed to a product specialist. Resolutions enable future product updates, making users a participant in improving the technology.
- A community driven knowledge provides a vast amount of information as well as resources for assistance.
Also read: The Growing Value of a Microservice Architecture
VMware may be a victim of its own success. It is like navigating through a labyrinth to attempt to make sense of the various product names and versions of a legion of virtual apps, as well countless virtual tools. The hypervisor is actually ESXi but that name is largely buried these days within the larger vSphere package. Similarly, even vSphere can get a little lost within the many other VMware offerings. Yet competitors have a rough time trying to pry business away from those organizations thoroughly invested in VMware technology. After all, it has been the market leader for years and boasts a breadth of virtualization products and features second to none. This includes a vast array of compute, storage, cloud, and networking tools. Those wishing to avoid complexity or lacking the requisite in-house skills will probably venture elsewhere.
- It has been rearchitected with native Kubernetes to allow users to modernize the 70 million+ workloads now running on vSphere.
- Containerized applications can be run alongside existing enterprise applications in a simple using vSphere with Tanzu.
- Developer-ready infrastructure helps to align DevOps and IT teams, and simplify cloud operations.
- Scalability: Deliver Monster VMs designed for SAP HANA, Epic Operational Databases, and more. This enables a vSphere infrastructure to support 50% more hosts per cluster.
- GPUs: Provide AI/ML infrastructure using GPUs to simplify software upgrades, patching and firmware updates, as well as add greater security to hybrid cloud infrastructure.
Proxmox VE (virtual environment) is another open-source server management alternative. It integrates KVM hypervisor and LXC, software-defined storage, and networking functionality on a single platform. The user interface makes it relatively easy to manage VMs and containers, high availability clusters, or integrated disaster recovery tools. Based on Debian GNU/Linux, it uses a customized Linux kernel. This platform would be an option for those comfortable with the nuances of open source code.
- Low cost due to the use of open source
- Virtualize demanding Linux and Windows application workloads: you can run both Windows and Linux in VMs where each VM has private virtualized hardware: a network card, disk, graphics adapter, etc.
- Can dynamically scale computing and storage
- Hands-on training is available to master the concepts and components of Proxmox VE.
- Enterprise features are relatively easy to manage.
After launching Microsoft Hyper-V in 2008, it took a while for it to establish itself. Today it stands as a major competitor to VMware. Anyone committed to Azure, Office 365, and Windows is unlikely to look elsewhere for server virtualization. However, it suffers from the same issue as VMware – an overabundance of riches. An endless array of products, features, and sites makes it hard to even find Hyper-V on the Microsoft website. It appears to have been relegated to a feature of large tools such as Windows Server or Microsoft Azure. It remains to be seen, then, whether that status will see it prioritized internally on the product development front.
- Tight integration with Azure, Windows, Office 365, and other Microsoft products.
- Simplifies the expansion of establishment of a private cloud environment.
- Ability to form a common identity platform with Active Directory across all Microsoft platforms.
- Centralized management of all Windows, Azure and Hyper-V workloads running on-premises and in the cloud.
- Good protection for VM workloads from unauthorized access, with Shielded Virtual Machines for Windows Server or Linux workloads.
- Protect network traffic with Encrypted Subnets.
Nutanix AHV aims to simplify the world of server virtualization. It does away with the model that views virtualization as a complex layer of the IT stack that is licensed, deployed, and managed separately. Instead, Nutanix AHV offers a secure, enterprise-grade virtualization solution that can provision and optimize VMs and containers, monitor infrastructure and application performance, scale your environment, and automate mundane IT operations. Nutanix is a potential candidate for startups that have not yet become invested in one of the major platforms, or companies wishing to completely overhaul their entire infrastructure.
- Virtualization management is combined with Nutanix HCI (Hyper-Converged Infrastructure.
- Smooth implementation of security, network microsegmentation, as well as built-in configuration audit and remediation.
- Lower operational costs reported compared to other virtualization solutions.
- AHV is tuned to deliver optimal application performance on Nutanix HCI for the demanding enterprise applications.
- HCI software keeps data local to the application to ensure high performance, while decreasing network traffic.
- Machine learning technology balances resource consumption.
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Virtuozzo Hybrid Server delivers a mix of system containers, hypervisors based on optimized KVM, and software-defined storage. Though not as well known as Citrix, Hyper-V, or vSphere, Virtuozzo powers more than five million virtual environments. It claims to have better performance and to have twice the density of VMware. It includes AES-256 at-rest encryption and has a hypervisor core built on top of open-source KVM. Those wishing to consolidate and simplify containers, hypervisors and storage should consider Virtuozzo.
- Its open source approach efficiently makes use of existing hardware.
- Virtuozzo containers are based on the Linux kernel and offer good performance.
- Security is built-in via encrypted containers to protect production workloads.
- Compatibility with KVM
- Integrated with software-defined storage and networking.
Oracle VM VirtualBox
Oracle VM VirtualBox is a free, open-source hosted hypervisor for x86 virtualization that was developed initially by Innotek, acquired by Sun Microsystems and then by Oracle. It can be installed on Windows, macOS, Linux, Solaris, and OpenSolaris. VirtualBox is being constantly updated with new features, and wider support of systems, platforms, and applications. This general-purpose virtualizer for x86 hardware is not just for server virtualization. It also applies to desktop and embedded applications. But it is really only applicable to those with Oracle-rich environments.
- For enterprise as well as home use.
- Freely available as open source software under a GNU license.
- VirtualBox runs on Windows, Linux, Macintosh, and Solaris hosts.
- Supports guest OSes such as Windows (NT 4.0, 2000, XP, Server 2003, Vista, Windows 7, Windows 8, Windows 10), DOS/Windows 3.x, Linux (2.4, 2.6, 3.x and 4.x), Solaris and OpenSolaris, OS/2, and OpenBSD.
PowerVM is a feature of IBM servers such as Power5, Power6, Power7, Power8, Power9 and Power10 and is required for support of IBM micro-partitions and other advanced features. Support is provided for IBM i, AIX, and Linux. IBM PowerVM can consolidate multiple workloads onto fewer systems, increasing server utilization and reducing cost. It is a secure and scalable server virtualization environment that is applicable to AIX, IBM i, and Linux applications running on the IBM Power Systems platform.
- Scale out or scale up virtualized deployments without underlying performance penalties
- Helps to provide cloud services faster by automating deployment of VMs and storage.
- Eliminate scheduled downtime by deploying live mobility between servers
- Optimized for AIX, IBM i, and Linux systems running on the Power platform.
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