Virtualization showdown: Microsoft Hyper-V 2012 vs. VMware vSphere 5.1

[ Editor's note: This article has been revised to underscore the fact that we tested VMware vSphere with vCenter Server but we tested Windows Server 2012 Hyper-V without System Center 2012, and therefore these reviews do not constitute a straightforward comparison. ]

Any comparison of Microsoft's Hyper-V versus VMware's vSphere has to take into consideration a number of different factors. First, there's the target customer and the features required for different sizes of deployments. The needs vary widely depending on the number of virtual machine instances, and these requirements will drive the architecture and configuration choices. Second, there is the topic of management, which is also tied closely to the size of the installation. Beyond these considerations are a number of other issues, including cost, performance, scalability, and usability.

It was once a truism that Microsoft's solution was for small shops and VMware's was for large deployments, but that is no longer the case. VMware has plenty to offer small shops, and Microsoft has the features to compete at the high end. Microsoft and VMware both make it easy to start small and add capabilities as your virtualization environment grows. But they take different paths to this goal.

[ Read the Microsoft Hyper-V 2012 review | Read the VMware vSphere 5.1 review | Read InfoWorld's review of VMware vCenter Operations Manager | Get virtualization right with InfoWorld's 24-page "Server Virtualization Deep Dive" PDF guide. ]

True to form, Microsoft bundles the full gamut of virtualization capabilities into the operating system. With Windows Server 2012, or the free Hyper-V Server 2012, you can create high-availability Hyper-V clusters and tap advanced features such as live VM and storage migration, VM replication, and even network virtualization. As the numbers of hosts and VMs grow, you can beef up the management and automation capabilities by deploying System Center 2012.

By contrast, VMware vSphere includes the central management system, vCenter Server, as part of the deal. While you can virtualize servers to your heart's content using the free VMware ESXi hypervisor, the vCenter Server is needed to implement high-availability and unlock features such as live migration, replication, and the distributed virtual switch. These capabilities and more are available on a sliding scale as you move up the ladder of vSphere editions.

Targeting the small business customer

No matter how big or small your environment is, your number one priority will be to keep your servers running. High availability (HA) -- which involves detecting when a physical host is down and rebooting its guest VMs on another host -- is a capability that will matter to shops of any size. Both Microsoft and VMware put HA within a small shop's reach.

The ability to create high-availability host clusters is not only provided in both Windows Server 2012 Hyper-V and the free Hyper-V Server 2012, but Hyper-V can now leverage new capabilities in SMB 3.0 that give even the smallest shops the ability to stand up an HA cluster using low-cost servers and commodity SAS disk drives. You no longer need a Fibre Channel or iSCSI SAN.

With Windows Server 2012, Microsoft also introduces Hyper-V Replica. Hyper-V Replica provides unlimited host-to-host replication of virtual machines without shared storage. In other words, you don't need clustering but you can replicate to a cluster if you have one. Enabling replication is simple, and it's fully configurable from the Hyper-V Manager client.

VMware brings high availability to small shops with the vSphere Essentials Plus edition, which lets you create an HA cluster of three hosts. For those wanting to skirt the costs of an expensive SAN or NAS, Essentials Plus includes the vSphere Storage Appliance (VSA), software that allows you to implement HA by turning the internal storage of three vSphere hosts into a single, redundant, shared storage pool. Essentials Plus also includes host-to-host VM replication.

Nearly as important as high availability itself is live VM migration. The ability to move running virtual machines from host to host, without disrupting applications and users, live migration can mean the difference between uptime and downtime when the time comes for hardware maintenance or upgrades.

By automating live migrations based on resource consumption and thresholds, you can effectively balance the VM workload across all of your virtualization hosts. This is a feature that becomes important as you increase the number of hosts and the number of VMs per host. Automated VM load balancing is available in VMware's Enterprise and Enterprise Plus editions, and it requires System Center 2012 to be implemented with Hyper-V. VMware can also automate workload balancing across multiple storage devices; storage load balancing is available only in the Enterprise Plus edition.