When PGS needed to upgrade its exisiting data-centre facility due to an expansion in business, it turned to original partner Keysource, says Rob Elder
In 2008, PGS appointed Keysource to design, build, install and manage phase one of a high performance data centre that would significantly reduce power usage to achieve considerable cost savings and reduced carbon footprint. PGS uses vast amounts of data that is vital to the success of its business, so it needed a solution that would provide safe and sufficient storage and enable deployment of high-density HPC hardware.
The data centre was the first to adopt Keysource’s ecofris, the scalable, free-cooling solution that does not require the use of additional chillers until outside temperatures reach 24 deg C. This means that additional power for cooling is only needed for between 80 to 100 hours each year, because the system is able to make the most of low UK ambient temperatures in combination with adiabatic cooling.
However, due to an expansion in business, changes in technology and because of the low cost of computing at the Weybridge facility, PGS’s requirements had outgrown those used for the original design. In 2012, PGS engaged with Keysource to start developing the design for phase two. The companies worked together to further innovate and engineer an upgrade to surpass the success of the first phase.
The original system
The original design used a through wall airflow with air drawn through the IT equipment ducted into a ceiling plenum and then back to the cooling units. This tight control on airflow meant the design could accommodate 30kW in any rack. Keysource found it could achieve a highly efficient solution by recirculating the air within the data centre and not using direct fresh air.
Combined with an adiabatic system meant it could deliver an annualised *PUE L2,YC of 1.15, while maintaining a server inlet temperature consistent across the entire space of 22 deg C +/-1 degree.
The PUEL2,YC measure for PGS is a Category 2 measurement of PUE (as defined by the Green Grid and a 12 month total kWh consumption). Power usage effectiveness (PUE) is the industry-recognised metric for infrastructure energy efficiency for data centres, developed by The Green Grid Association and is the ratio of total facilities energy to IT equipment energy.
To deliver the same inlet temperature at the highest external ambient conditions, Keysource integrated a water-cooled chiller into the ecofris design to provide the mechanical cooling, only to top up the free cooling system.
As a result PGS ended up with two systems each with a 400kW chiller, which ran for only 50 hours a year on average.
Keysource addressed the need for better use of resources with the new design by incorporating a cooling solution that does not contain any chillers. As it does not use direct fresh air, it removes the need for any backup system. By recycling 100 per cent of the air within the data centre, Keysource can dynamically control the inlet temperatures based on optimum performance conditions.
This ensures IT equipment is well within its design operating parameters and the facility is at its most efficient all of the time. Any potential issues with high temperatures at the back of the racks is removed with the rack design, using a solid rear door and chimney.
The upgrade has increased power density by approximately 50 per cent, with the total IT capacity now 2.7MW This has been achieved within the same internal footprint. The facility now boasts 188 rack positions, supporting up to 30kW per rack.
By upgrading the existing cooling system to incorporate a chillerless design, this reduces the project capital expenditure and ongoing operational expenditure without comprising on availability and performance. It is this successful combination of factors that has been recognised by the industry professionals judging the latest Uptime Institute award.
Future for the technology
Moving forward we see an overall reduction in IT power through improved design and innovation in the IT layer but in turn this will mean increasing densities.
Typically for most enterprises the average power will be between 8kW to 10kW in a rack, so flexibility is essential. With efficient systems not requiring chillers for most of the time, the adoption of chillerless design will increase. But this will always be weighed up against the risks involved with direct fresh air systems and the considerations of availability and cost of other resources, such as water for adiabatics.
Reducing the overhead of power for mechanical cooling is becoming as an important part of design as reducing the operating costs. This is especially true where power capacity is restricted and for commercial providers who charge for IT power, where we see that up to 40 per cent more IT can be deployed with the same mains supply.
Rob Elder is director of Keysource