Curt Frierson, EVP Technology and Education
Technology has become well known for its steady stream of buzzwords. At any point in time, there are numerous technology-related terms or phrases that promise to revolutionize the industry. Some of these catchphrases do have a dramatic effect on the technology world, but many quietly die off over time. Of all of the current technology buzzwords, however, virtualization is one that may be the most disruptive force on the future of network computing. In fact, IT research firm Gartner predicts, “Virtualization will be the highest-impact trend changing infrastructure and operations through 2012.”
What is virtualization and why is it attracting so much attention? In reality, virtualization comes in many forms. The most widely used form today is server virtualization, which is simply the process of running multiple server environments on a single physical device. This is accomplished by inserting a thin software layer (known as the hypervisor) which directly interacts with a server’s hardware, including memory, cpu, and disk drives, and allows it to be shared by multiple operating systems. Common hypervisors available today are VMWare, Citrix’s XenServer, and Microsoft’s Hyper-V. With the exception of Hyper-V, most hypervisors can run as the operating system of the server itself. When configured in this manner, the hypervisor is known as the “Host OS”. Any operating system(s) installed on top of the hypervisor is referred to as a “Guest OS”, “Virtual Machine (VM)”, or “Virtual Server”. In other words, a physical server will have only one Host OS but can support many VMs.
The obvious benefit of this approach is the reduced need for physical hardware. This feature, though, is only the beginning of the advantages that virtualization can provide. Reducing the number of servers in your server room or data center brings many benefits of its own. First, running multiple environments on a single hardware system allows for more efficient utilization of existing resources. Most application servers use only a small percentage of the hardware capabilities a server provides. The more servers an organization has, the more resources get wasted by being underutilized. Second, scalability is greatly enhanced through virtualization. Additional virtual servers can be added quickly without the need for procuring physical hardware. Next, reducing the number of physical servers reduces power and cooling costs. The extent of this benefit is dependent on the size of the existing data center but can be an overlooked cost savings when calculating ROI. Additionally, having less physical machines to manage can improve the productivity of administrators. Virtualization management software has many tools to simplify server management, such as a consolidated view and configuration console for all virtual servers. Lowering the number of physical machines also reduces the number of server replacements and hardware failures, saving maintenance time involved with these activities. All of these advantages relate directly to the reduction of physical hardware allowed through server virtualization. Noticeably, cost savings is not listed as a key benefit. While it is true that there is less cost involved in server hardware, the licensing costs of virtualization software and maintenance can quickly evaporate hardware savings. Additionally, more powerful servers are typically used in order to allow a higher number of virtual machines to run on a single device. This translates into a higher cost per physical server, yet still a lower overall hardware cost.
While less physical hardware provides several advantages in itself, the inherent capabilities of virtualization create the biggest value. Server virtualization provides enormous improvements to the disaster recovery process. Snapshots can be taken at regular intervals of the entire virtual machine. These snapshots can be backed up to offline storage or replicated to another physical server where they can be turned on at a moment’s notice. These snapshots are the entire server, not a backup of the individual file system. This means that a virtual server can be restored in its entirety to any virtual environment, regardless of the physical hardware involved, without the need to reinstall operating systems and applications or perform fragile system state restores. When all of an organization’s servers are virtualized and backed up, they can actually recover their entire enterprise exactly as it was at the time of the last snapshot backup.
VMWare’s VI3 Enterprise provides additional, almost unbelievable, capabilities. By utilizing shared storage, such as a SAN, multiple physical servers can be connected together in a pool of resources. Virtual servers can be added to any physical machine within the resource pool. If a physical machine experiences a failure, the virtual machines running on the physical server can be automatically moved to one of the other machines in the pool with little or no downtime and no administrator action required. For planned hardware maintenance, administrators can move virtual machines running on the server”on-the-fly” with absolutely no downtime. The virtual environment can even be configured to automatically move resources based on the amount of available of resources of a physical machine, such as CPU or memory. In other words, a virtual machine can automatically move to another physical machine if the one it is currently on is becoming low on available memory. These features provide significantly better availability than is offered through traditional network architectures.
These features of virtualization are only the beginning of what is to come with this technology. In fact, server virtualization is only one form of the virtualization capabilities available today. While VMWare is currently the market leader that others (including Microsoft) are chasing, more and more vendors are entering the virtualization arena. This will continue to drive costs down and bring new features to the market. However, the current advantages that virtualization provides are compelling enough to warrant serious consideration. All signs point to this technology to dramatically alter the future of networking technology as we know it. The question is not “if” this technology will become mainstream. It is a question of “when”.