Managing License Compliance in Virtualized Environments

The Rise of Virtualization Technology

Datacenter server virtualization is one of the hottest trends in IT today.  The adoption of this trend has resulted in benefits including better utilization, flexible performance and load balancing, as well as reduced power consumption.  Datacenter server virtualization saves space, power and hardware costs for thousands of enterprises by consolidating physical machines. The reduction in the number of physical machines is achieved by increasing hardware (CPU and memory) utilization from a typical 10-15% to as much as 75-85%.  In addition to the savings on hardware purchases, there are reduced cooling requirements and maintenance cost savings associated with fewer machines. Energy cost savings have been estimated to be in the range of $300 to $600 per year for each server that is eliminated by virtualization. The total savings can be in the millions of dollars per year for large enterprises.

Server virtualization has broken the bonds of legacy datacenter IT architecture in which a single application and a single operating system (OS) run on each server. In the virtual datacenter, multiple applications and operating systems can run securely on one server. It is this capability that allows hardware utilization to increase dramatically. The trend is to take it a step further and create pools of shared hardware resources that include not only multiple servers (compute resources), but also I/O and storage resources, that can be efficiently and dynamically allocated to many virtual machines. This virtual infrastructure provides increased flexibility, high availability and scalability to meet today's enterprise datacenter needs.

Server virtualization allows multiple software instances of a computing platform to run concurrently on one physical machine.  These virtual machines (VMs) are capable of running an operating system and a set of applications. Each VM may run a different OS -- Windows, Linux, UNIX, etc. -- or different versions of the same OS, depending on the needs of the software applications. This provides tremendous flexibility and security. The dominant approach to server virtualization is through a thin software layer-hypervisor-between the physical machine and the VMs. The hypervisor is installed on the "bare metal" of the server, taking the place of the traditional OS. Hypervisors dynamically allocate hardware resources to each VM. This is the approach taken by the leading server virtualization solutions from VMware (ESX Server), Citrix (Xen) and Microsoft (Hyper-V).

The Implications of Virtual Environments for SAM