The terms "virtualization" and "virtual machine" have been lingua franca for the better part of a decade, tossed around freely in every corner of the IT world. If you didn't really know what they meant, you just nodded knowingly to get through the meeting.
If you're already savvy in the area of virtualization, forgive us as we refresh our memories with a look at the core concepts. However, feel free to look through the recent resources below and get caught up on virtualization developments from the past couple of years.
Actually, virtualization set down its roots more than 40 years ago, and certainly joined the computing lexicon in the 1970s when IBM introduced its VM (virtual machine) as sort of an overlay operating system. In the simplest sense, VM allowed an IBM mainframe to host two operating systems at the same time, allowing the users and applications employing each to think they were running on a dedicated machine.
Today, virtualization is a concept applied to servers, networks, desktops, and storage. But it is server virtualization that drove the idea forward -- and, no, you don't need a $12 million mainframe to do it.
As the idea of shared, networked computing resources (servers) advanced, it was common practice to dedicate a single server to an operating system and the applications that it supported, even if that software only used a tiny fraction of the hardware's capability. On the other hand, if the workload maxed out the hardware, the only solution ensuring uptime was to buy a bigger server and reinstall all of the software on the new platform.
Virtualization techniques initially focused on that hardware utilization challenge, giving IT administrators the flexibility to run applications on whichever hardware platform was available, even across multiple servers.
So some of the jobs running on a nearly maxed-out system could be shifted easily to the underused system as needed by letting those applications run in virtual machines without users knowing which hardware it was running on.
Server virtualization provided IT with the ability to support applications as demand grew, and to consolidate other applications from underutilized servers. Cost savings on hardware and software licenses and ease of management were the key driving factors. As server virtualization has evolved, not just with software but with specially designed hardware enabling virtualization, benefits beyond cost have emerged.
Yes, virtualization still aids consolidation and load sharing. It also can support scaling for global growth of the company, disaster recovery strategies, use of VMs for development and test, integration of digital telecommunications (VoIP phone) applications, and -- with the growth of software-defined networking -- virtual networks on the same types of servers that host email and office applications.
Today, IT managers can choose from a variety of software options to implement server virtualization, with hypervisors -- which create and manage virtual machines -- and other management tools. Key software players and platforms include VMware, Microsoft, Red Hat, the Linux-based KVM, and Citrix with its open-source Zen technology. In addition, hardware companies such as Intel are designing their processors with virtualization capabilities.
Need more details on server virtualization? Browse these resources:
- The Software-Defined Data Center: Potential Game Changer. Extending virtualization across multiple data center technologies, the SDDC is intended to provide IT pros with improved flexibility in managing resources.
- Server SANs And Healthy Paranoia. Server SANs, which dedicate storage resources to a server are targeted at virtualization admins as buyers.
- Data Protection Must Change In Virtualization Age. While server virtualization can make life easier for the IT admin, it can complicate matters for IT security, particularly when it becomes challenging to figure out which VMs are running on which platforms.
- Compromising Virtualization. Server virtualization is generally considered a first step into cloud computing. However, instance storage is a concept that can improve performance in a virtualized server/cloud environment, but also presents some challenges.
- Governments Missing Out On Virtualization Savings. Some government agencies say that virtualization has led to cost savings, but there's a lot more to be done.
- Microsoft, Others Closing In On VMware In Server Virtualization Market. VMware was the dominant provider in the virtualization market for a long time but by 2012 Microsoft, Citrix, and KVM were helping to level out prices.
- Virtualization Vs. Networking. In addition to the security issues that virtualization can present, it also can overload a network with data and requests for data flowing from many VMs.
- How Server Virtualization Works. Still need to know more about the basics of virtualization? Check out How Stuff Works and this general description.
Figure 1: Server Virtualization at a Glance