Virtualisation in the datacentre – all it's cracked up to be?

Virtualisation technology has gradually grown over the past decade and has changed the way in which datacentres are currently developed and configured. While there is much attention given to both its benefits and advantages, it is important that resellers and the channel understand there are many hidden costs involved with providing a virtualised strategy for their customers. It is also important to understand the impact that its introduction will have on the tangible and physical infrastructure upon which they run: the datacentre.

Virtualisation – what is it?

At the most basic level, virtualisation decouples hardware and software and is commonly used at server level. Physical servers are converted to virtual servers on one machine. So if one application fails, the other applications are unaffected, and, in theory allow the IT manager to run many applications on the same server.

Heralded as a way for organisations to increase efficiency and reduce carbon footprints, server virtualisation has been widely adopted by datacentre managers. Consolidating hardware not only reduces costs, but also allows extra space, helping to ensure business continuity. It also helps extend the value of existing datacentre facilities.

Challenges faced with virtualisation

The benefits of this technology and service delivery model are well known, understood, and increasingly being taken advantage of. However their effects on the datacentre’s physical infrastructure are less understood.

Virtualisation involves the consolidation of multiple servers in which applications can be stored on a virtual machine. However, this poses problems to the power and cooling of the datacentre. While virtualisation may reduce overall power consumption in the room, virtualised servers tend to be installed and grouped in ways that create localised high-density areas that can leading to ‘hot spots’.

Hot spots develop due to high power density in various racks as virtual applications are moved around. Areas of high density provide cooling challenges, which is surprising given there are less servers to be cooled. However, if these hot spots are not dealt with, the entire reliability of a datacentre will be affected.

Cooling the high densityThere are several ways in which facility managers can manage hot spots and cooling whilst allowing the virtual machines to run unrestricted. The first is to use the ‘hot aisle/cold aisle’ method of temperature control, which is where hot or cold air is captured and held in a certain area so that the maximum benefit can be derived from cooling activities.

Another common method is to simply ‘spread out’ the high density racks throughout the datacentre floor. By doing this, no single racks will exceed the power density and cooling performance is more predictable. The one benefit of this method is that no new power and cooling infrastructure is required. However this approach does bring its disadvantages including high cabling costs, floor space consumption and racks that may be wasting power.

Management of virtual servers

It is important for facility and datacentre managers alike to monitor their servers, whether they are virtual or physical. The last couple of years have seen the emergence of new approaches to monitoring and management tools such as datacentre infrastructure management (DCIM). These technologies help IT professionals gain an overview of datacentre operations and the progress of virtualisation strategies.

It has become clearer that some virtual servers may not be as productive as expected or are under-utilised, chewing through power, costing the datacentre more money than it should. DCIM provides a new level of insight that can be relayed back to C-level executives. By identifying key system performance indicators such as the levels of server hosting and detecting power usage down to the individual machine, DCIM strategies help datacentre managers identify a plan of action. This is through identifying corrective measures and learnings that can be used to fine tune server infrastructure and virtualisation management strategies for optimum performance.

Despite the challenges that are appearing in the datacentre, virtualisation is still an important tool to businesses and is providing valuable revenue for the channel. Tools to understand virtual server usage and cooling techniques designed to deal with hot spots are also vital for any facility manager. Once these finer details are ironed out and are understood by both the vendor and the channel, then we will begin to see the true effectiveness of virtualisation.