Once you choose the type of hypervisor that fits your needs, you need to choose the best hypervisor technology...
for your infrastructure. Hypervisor products from the major virtualization vendors have their pros and cons, so consider the features of these hosted and bare-metal virtualization hypervisors before you make your decision.
Bare-metal virtualization hypervisors
VMware ESX and ESXi
VMware has the most mature hypervisor technology by far, offering advanced features and scalability. However, VMware’s bare-metal virtualization hypervisor can be expensive to implement because of its higher licensing costs. The vendor does offer a free version of ESXi, but it’s very limited and has none of the advanced features of the paid editions. VMware also offers lower-cost bundles that can make hypervisor technology more affordable for small infrastructures.
Microsoft Hyper-V has emerged as a serious competitor to VMware ESX and ESXi. Hyper-V lacks many of the advanced features that VMware’s broad product line provides, but with its tight Windows integration, Microsoft’s hypervisor technology may be the best hypervisor for organizations that don’t require a lot of bells and whistles.
Citrix XenServer is a mature platform that began as an open source project. The core hypervisor technology is free, but like VMware’s free ESXi, it has almost no advanced features. Citrix has several paid editions of XenServer that offer advanced management, automation and availability features. But despite offering a stable bare-metal virtualization hypervisor, Citrix struggles to compete with Microsoft and VMware on hypervisor technology.
Oracle VM is Oracle’s homegrown hypervisor technology based on open source Xen. If you want hypervisor support and product updates, though, it will cost you. A simple, no-frills hypervisor, Oracle VM lacks many of the advanced features found in other bare-metal virtualization hypervisors. As with XenServer, the development cycle of Oracle VM is longer and limited, which makes it hard to compete with VMware and Hyper-V. One advantage of Oracle VM, though, is that it’s certified with most of Oracle’s other products and therefore includes no-hassle support.
Hosted virtualization hypervisors
VMware Player is a free virtualization hypervisor. This hypervisor technology can only run a single virtual machine (VM) and does not allow you to create VMs. VMware Workstation is a more robust hypervisor with some advanced features, such as record-and-replay and VM snapshot support. VMware Workstation retails for $189 and has three major use cases: for running multiple different operating systems or versions of one OS on one desktop, for developers that need sandbox environments and snapshots, or for labs and demonstration purposes. VMware Fusion is the Mac version of Workstation, which only costs $89 but lacks some of the features and abilities of Workstation. This hypervisor technology is better suited for running Windows and Linux on Macs.
VMware Server is a free, hosted virtualization hypervisor that’s very similar to VMware Workstation. However, VMware Server lacks some of the features of Workstation and only supports a single snapshot per VM. This hypervisor technology is designed to run headless with a network-based administration utility and is optimized for running more server-like workloads. VMware has halted development on Server since 2009, but it works well as a no-frills hosted hypervisor and is an easy alternative to using the free version of ESXi.
Microsoft Virtual PC
Microsoft acquired the Virtual PC technology from Connectix in 2003 and re-branded it as Virtual PC 2004. The latest version of this hypervisor technology, Windows Virtual PC, only runs on Windows 7 and only supports running Windows operating systems on it. A common use case for Virtual PC is running legacy apps on a Windows 7 desktop using older versions of Windows. Virtual PC is free and is also available for users with Windows 7 Professional, Enterprise or Ultimate licenses as a pre-packaged appliance called Windows XP Mode.
Oracle VM VirtualBox
Oracle VM VirtualBox is a mature virtualization hypervisor that’s suitable for many needs and use cases. VirtualBox hypervisor technology provides reasonable performance and features if you want to virtualize on a budget. Despite being a free, hosted product with a very small footprint, VirtualBox shares many features with VMware vSphere and Microsoft Hyper-V. Oracle VM VirtualBox provides a decent alternative to more expensive hypervisors for both server and desktop virtualization.
Red Hat Enterprise Virtualization
Red Hat’s Kernel-based Virtual Machine (KVM) has qualities of both a hosted and a bare-metal virtualization hypervisor. KVM turns the Linux kernel itself into a hypervisor so VMs have direct access to the physical hardware. KVM in Red Hat Enterprise Virtualization offers many enterprise-level features and comes with a Windows-based management server for managing multiple KVM hosts. This hypervisor technology is not free, however, and while KVM has enterprise features and scalability, it lacks some of the more advanced features and application programming interfaces that VMware and Microsoft offer.
Parallels is known for its popular Parallels Desktop for Mac hypervisor, which is very similar to VMware Fusion. Parallels also has a desktop version of its hypervisor technology that runs on both Windows and Linux. Plus, it has a more powerful edition called Parallels Server for Mac, which has greater scalability and more advanced features. Parallels’ hypervisors are also pretty mature, having been first launched in 2005. They offer a very low-cost, feature-rich hosted hypervisor that can be used for a variety of purposes.
Which product should you choose?
You can evaluate every virtualization hypervisor for free, so spend some time on the ones that appeal to you and make sure they meet your requirements. Don’t try to make hypervisor technology do more than it was designed to do. If you run a busy Exchange server on a simple hosted hypervisor, for instance, it’s probably going to be very slow. Also remember that VMs are portable and easily convertible, so if you choose what you think is the best hypervisor technology and discover you don’t like it, there are tools to convert it to another hypervisor platform.