It wasn't that long ago that SQL Server was one of those workloads that nobody considered virtualizing. Common reasons for not virtualizing SQL Server were that it was too resource intensive or that virtual machines (VMs) didn't provide enough performance. However, a lot has changed. Nowadays, it's common for SQL Server workloads to be virtualized. Only the most resource-intensive workloads defy the move toward virtualization. In fact, it's now almost a standard practice for organizations to routinely deploy VMs for all new servers. Departments and branch offices need reasons not to virtualize a server if they want to put in a physical box, which for the most part is a nonissue because most users vastly prefer the quicker deployment that virtual servers allow. In 2011, Gartner Research predicted that 50 percent of all workloads would be virtualized by the end of 2012, which would equate to about 58 million VMs.

The rise in virtualization is partly due to the fact that organizations have learned about some of the deployment and high-availability benefits offered by virtualization. However, I think the more important factor is that virtualization platforms such as vSphere and Hyper-V have matured enough to provide the levels of performance, scalability, and reliability that are required by production workloads—or, to use the new term, Tier 1 applications. The technological change that made this possible was the advent of the type 1 hypervisor that runs on bare metal. VMware pioneered this with ESX Server. Today, VMware's vSphere 5.1 and Microsoft's latest Windows Server 2012 Hyper-V are the most common type 1 hypervisors. The performance of the type 1 hypervisor has been proven in real-world server consolidation deployments by companies from all over the world, as well as in lab tests by both VMware and Microsoft. In the labs, both companies were able to exceed 1 million I/O operations per second (IOPS) in a VM running on their respective platforms. One million IOPS will provide all the scalability that the vast majority of businesses will ever need to support their mission-critical applications.

Like you might expect, given its proven track record and longer time in the virtualization market, VMware VSphere. Most analysts' estimates put it at about 75 percent market share, with Microsoft Hyper-V a growing 20 percent of market share. One of our recent SQL Server Pro Instant Polls reflected similar numbers. We asked, “Do you use VMware products in your virtualized SQL Server environment?” Sixty-one percent answered yes; 17 percent stated that they use Microsoft Hyper-V; and 22 percent answered that they don't have virtualized instances of SQL Server databases. At first, you might think that 22 percent  with no virtualization is high, but when you consider the critical nature of SQL Server systems and the fact that most organizations don't fix it if it's not broken, it makes perfect sense. Another interesting study performed by the Enterprise Strategy Group (ESG) in 2011 showed that 70 percent of organizations were already using more than one hypervisor. The multi-hypervisor situation is sure to change over the next year as Microsoft's new, more-capable Windows Server 2012 Hyper-V continues to gain market share.

 With today's latest virtualization products, does the virtualization platform you choose really make any difference? With earlier versions of Hyper-V, it did make a difference. The main issues were that scalability was limited to four vCPUs, and features such as live migration, storage live migration, and disaster recovery options weren't equal to what vSphere offered. The limitation of four vCPUs could really affect virtualized SQL Server implementations. Now, with VMware vSphere 5.1 and Microsoft Windows Server 2012 Hyper-V, the answer is essentially no. The two platforms are basically equal, and both are definitely capable of supporting high-performance production workloads. Sure, each has certain advantages, but the popular saying is, "Now Hyper-V is good enough"—which is true. In some ways, the new Hyper-V even exceeds vSphere 5.1 by offering better scalability and by supporting greater VM and host RAM and CPU capabilities. In today's IT landscape, virtualization has become a commodity. The real question moves up to the next level—the private cloud and management of your virtualized infrastructure—which is where the true battle for IT mindshare is shaping up.