How to build a green virtual data centre

Give your virtual data centre a green makeover with these energy-efficiency tips from Andrew Cross, sales director at reseller Sol-Tec.

Meeting green aspirations in the data centre can be tricky when trying to marry financial objectives, legacy equipment and the vast array of green products offered by vendors. However, there are practical steps that can be taken to help meet your green objectives and improve your bottom line.

Server virtualisation
Server virtualisation is the traditional starting point for creating a green data centre. However, virtualisation has moved on considerably since its re-incarnation from mainframe computing several years ago. Concerns over server performance are now tempered with VMware claiming up to 85% native performance with its vSphere 4, and Parallels using near-native performance technologies.

One initial aim of server virtualisation was to address physical server sprawl. IT managers now face a fresh challenge -- virtual server sprawl. With vendors like Microsoft, VMware and Citrix now offering free server virtualisation software, it is easier than ever to create and deploy servers for every conceivable need. These are often left in the server farm, unnecessarily using physical resources. Vendor-agnostic assessment software like VReady from Lanamark will provide reports that show how your virtualised data centre could look using technologies from Microsoft, VMware, Citrix and Parallels. Reassessment of fully or partially virtualised data centres can be as revealing as assessing a data centre for the first time.

Decommission unused servers
The larger the data centre, the more likely it is that there will be servers running without providing services. Decommissioning unused servers saves power, release software licensing for use elsewhere, reduces maintenance charges and lowers the required cooling level. BT has saved 5.3 GWh per year by adding server decommissioning to its virtualisation plans and associated cooling reductions.

Upgrade existing UPS systems
This is often overlooked, but a refresh in uninterruptible power supplies (UPS) could reduce both power and heat. Newer UPS systems can provide up to 97% efficiency, meaning only 3% of power is leaked as heat. Older UPS models can leak as much as 30% power in the form of heat. Modular UPS systems like Symmetra from APC only use the power cells that are required.

Work more closely with facilities
The old adage is that IT uses the power but another department gets the bill. Working with facilities or finance to understand how power is purchased can ensure that any green benefits are highlighted. It is possible to provision required power to the data centre only from a reusable energy source. For example, Rackspace's hosting centre in Slough uses power supplied by Slough Heat & Power Limited from its biomass energy plant. Creating the green data centre extends beyond the IT only remit.

Reduce storage requirements
Single-instance storage (SIS) or data de-duplication is now an accepted and widespread practice and has helped to reduce storage requirements in data centres. However, the requirement of the data centre to provide files to users across the WAN has led to newer and complementary technologies like Local Instance Networking (LIN). This provides a local cache of used files at locations on the WAN, removing the requirement to interrogate the data centre.

For companies with high file transfers across the WAN, introducing LIN technologies can both reduce the workload on the data centre and reduce the usage of the WAN. Lesser-known vendors like Silver Peak are helping enterprises like Ernst & Young achieve WAN-wide benefits.

Storage virtualisation
Addressing the ever-growing requirement for storage by using existing available storage will both reduce capital expenditure and lessen the associated power and cooling demands of introducing new equipment. Thin provisioning allocates storage space only as the data is written, thus removing the need for pre-allocated storage. Technologies from vendors like NetApp and 3Par offer opportunities to maximise storage efficiency and reduce storage hardware.

Using benchmarks
Establishing a baseline from which the introduction of a greener strategy can be measured helps bring the new approach into a more formal business environment. Indicators such as electricity usage and costs are simple for all disciplines of a business to understand, and organisations like the Carbon Trust can assist a company in identifying business-wide energy measurements.

From a data centre perspective, more IT-specific measurements of physical server host uptime in the virtual data centre will prove useful indicators as to how energy efficient you really are. The Standard Performance Evaluation Corporation (SPEC) was formed to create a standardised set of relevant benchmarks that can be applied to the latest generation of servers.

Increase the temperature
Data centres are historically cold, as evidence suggests servers run better when it's cooler. But making a data centre too cold creates a high energy bill. With newer data centre hardware able to withstand a slightly higher temperature and humidity, a reassessment of the data centre temperature could be in order. Research from Hewlett-Packard concludes that for every one- to two-degree increase in temperature, a two to four% savings in cooling can be achieved. With average data centre temperatures running between 65-70 degrees, data centres running below this could see significant savings by adjusting the temperature.

Design improvements
Simple design changes to existing data centres can help reduce cooling requirements and associated cost. Inefficient air cooling and management, resulting from poor server orientation, inappropriate use of rack cooling and badly positioned floor vents, compound the problem.

Check that all rackmounted equipment is either cooling "front to back" or "back to front," and that multiple rows of racks do not compound the problem by sending their hot exhaust air into the neighbouring server's cool air intake. Proper use of available floor vents to maximise and complement rack airflow is important, too. For example, rearranging floor tiles to create hot aisle/cold aisle will bring airflow benefits.

Choose more manageable servers
When selecting new servers or blades for the data centre, attention should be given to the management of the components and their ability to switch off when in use. Configured correctly, this can bring considerable reductions in power consumption by automatically switching off unused components like CPUs. When combined with virtualised server resource management software, like VMware's Distributed Resource Scheduler, power utilisation can be maximised. For example, a data centre serving a U.K.-based workforce will see power consumption savings as unused server resources are powered -- not as they become unused.

Finally, it is worth noting that an increasing number of innovative green finance options are becoming available. For example, Salix gains funding from the Carbon Trust and works across all areas of the public sector, allowing interest-free grants. Grants pay for the initial capital expenditure with financial savings made by the organisation, being returned to the fund, until the original capital investment is repaid.

Properly planned and appropriately executed, a green approach to the data centre brings technical, operational and business benefits, and contributes to the wider effort to reduce our dependency on non -renewable energy resources.

 Andrew Cross is the sales director at reseller Sol-Tec and a contributor to 

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