Server virtualization and network management

Database and Network Journal, Oct, 2008 by Dirk Paessler

Server virtualization is the latest major technology trend in the data center. Gartner predicts that virtualization will be the highest-impact trend in IT infrastructure and operations through 2012.

Despite its limits, where server virtualization has been applied rigorously, it has both enormous and positive impacts on corporate power and cooling expenses as well as data center capacity. It can extend the lives of aging data centers and even allow some large organizations to shut down some of their data centers. And, this is just the first generation of virtualization's impact. A second generation technology, which allows multiple virtual servers to share a single operating system license, promises to allow even further consolidation. This can get to the point where 50-100 virtual servers run on a single physical box which can manage high-compute load applications that are considered poor candidates for first-generation virtualization.

Virtualization works by fleeing applications from the constraints of a single physical server. It allow multiple applications to run on one server, but equally important, it allows one application to use resources across the corporate network.

One of the promises of virtualization is the ability to allow applications to dynamically move from one physical server to another as the demands and resource availabilities change, without service interruption.

Virtualization also mandates the use of storage-area networks (SANs) and detached storage. This drives the network further into the center of the IT infrastructure and architecture.

From a security standpoint, centralizing multiple applications on a single box creates single points of failure, both in the physical server itself, and in its network connection.

When a virtualized server crashes, or its network connection slows or breaks, it impacts all the applications on that box. The implication for network planning is that a great deal more traffic will be centralized on a few large servers instead of spread out across a large number of smaller computers on the data center floor.

Also, virtualization works best with detached, rather than attached storage. This requires very fast, dependable network connectivity between servers and the storage devices on the storage area network (SAN). Organizations moving from attached storage, as part of virtualization, will create a large increase in network traffic. All of this increases the need for strong network management.

A highly virtualized environment lives or dies on the efficiency and dependability of its data network. Failure of a physical server, connection, switch or router can be very costly when it disconnects knowledge workers, automated factory floors or online retail operations from vital IT functionality.

Network management can provide vital information for planning and testing virtualized environments. For instance, determining which applications are not good candidates for virtualization is vital. The amount and character of network traffic can provide important clues towards identifying those applications

Why Server Virtualization

Server virtualization has come just in time for IT departments caught between the pressure to cut costs in the face of a developing worldwide recession, steadily increasing energy costs and maxed-out data centers.

Virtualization attacks the problem of the low utilization of single-application servers. These proliferate in data centers of medium to very large enterprises.

The server populations of many non-virtualized environments average about 20% utilization. The result is a huge waste of power, which is doubled since every kilowatt used has to be balanced with an equal amount of cooling to maintain the servers at optimal operating temperature.

This also has grave implications for the lifespan of data centers as increasing numbers of facilities run short of power, cooling and, in some cases, floor space despite the move to blade servers over the last few years.

Virtualization avoids this problem by automating the management issues of stacking multiple applications on a single server and sharing resources among them.

[ILLUSTRATIONS OMITTED]

This allows IT shops to increase their server utilization up to 80%. The impact of this on a large organization is demonstrated by the experience of BT in the UK. It achieved a 15:1 consolidation of its 3,000 Wintel servers and saved approximately 2 megawatts of power and $2.4 million in annual energy costs. This helped to reduce server maintenance costs by 90%, and BT disposed 225 tons of equipment (in an ecologically friendly manner) and closed several data centers across the UK.

This saving is even more remarkable because it involved only Wintel servers--BT also has a large population of Unix servers that were not factored into the savings.

Not only did BT achieve huge operating savings, partly by avoiding the need to build a new data center at an estimated cost of $120 million, it also received three top European ecology awards for the reductions of its carbon footprint from the program.