Data centre firm Equinix has expanded its UK presence by channelling $79m of capital to create its sixth London data centre, located in Slough.
LD6 is Equinix's third Slough-based data centre, and has "dark fibre" cables laid by the company to connect the LD4, LD5 and LD6 together, so the company's customers can scale up their server needs without having to shift hardware to and from different buildings.
Slough was the location of choice for the LD6, not only because of its proximity to sibling centres, but also because the area is the second point in the UK where the nation's internet connects to the global network exchange; the other is in London's Docklands.
Equinix boasts numerous customers in the financial sector, where heavy use of data is required for stock market speculation on a daily basis.
As such, Equinix customers require their servers to be close to the international internet exchange to minimise latency so that transactions can be carried out as quickly as possible. This has resulted in Slough becoming a major location for stock exchange trading systems.
Whereas some of Equinix's data centres have been created out of converted warehouses, LD6 is a bespoke building, custom designed to be as energy efficient as possible.
On a tour of the centre, V3 had the opportunity to see some of the building's key features that separate it from other Equinix data centres.
A building of two halves
LD6 is split into two parts, or "phases". Phase one offers a total of 8,000 square metres that can house 1,385 server cabinets across two data halls. Phase two will mirror this once construction is completed.
The space between the two forms a channel where vents on the building allow cool fresh air to be sucked into the centre's indirect fresh air cooling system.
A breath of fresh air
To make efficient use of energy, LD6 has a fresh air cooling system, rather than refrigeration or water cooling, to keep the server halls at a target temperature of 22 degrees Celsius.
Unassuming to look at, the cooling units use fans to extract hot air from the server halls into a heat exchanger, at the same time piping in cold air from outside the building.
The law of thermodynamics means heat is dissipated via the exchanger into the cold air, which is then exhausted out of the top of LD6. The cooled air inside the heat exchanger is then blown back into the data halls, where the process is repeated.
This cooling technique only requires power for the fans circulating the air, meaning it consumes less energy than other methods.
To ensure the air in the data halls is kept pure and dust-free, the hot and cold air streams never mix.
In hot weather the cooling units, which sit under a sturdy canopy on LD6's roof, need to be sprayed with cold water to keep the server halls at the target temperature. This water is extracted from a 350-metre deep external borehole, where it is then softened and stored in tanks to provide 48 hours of additional cooling.
A backup mains water supply also runs into the centre to be used if borehole water is not sufficient.
If additional cooling is needed, chilled water is pumped into the cooling units. The video clip below demonstrates how the air and water flow operates within the units.
Inside the data halls, currently awaiting customer servers, cooling is provided through an underfloor system and through the walls, which ensures that space in the data halls is maximised and used in an efficient manner.
Equinix is expecting a variety of cloud providers, such as Microsoft and Amazon, to join its enterprise customers, which the firm declined to reveal due to the sensitive nature of the sectors some of those companies occupy.
Equinix explained that the building was specifically designed around the cooling system in order to make LD6 the UK's first data centre to meet the Leadership in Energy and Environmental Design gold-standard.
A caged area in each data hall provides customers with an extra layer of physical security should they request it.
To prevent any risk of fire, LD6 operates a zero cardboard policy, under which servers must be unpacked in a separate logistics area to ensure combustible materials and dust are kept outside of the halls.
In the unlikely event of a fire, a water and nitrogen mist system is activated to suppress the flames by taking away the heat and oxygen. This method avoids excessively damaging servers in the data halls.
Power to the servers
The mission-critical nature of the applications and data running on Equinix customers' servers requires multiple layers of power backup to ensure the servers remain up and running in the event of an area-wide power failure in Slough.
Day-to-day power is provided by dual mains power supplies delivering 11,000 volts each. If both of these fail, an uninterruptible power supply (UPS) kicks in.
Four of these UPS modules supply each phase and are used in an "N+1" configuration, meaning three are active at all times, with the fourth kept as a backup in case one of the others fails.
Each UPS unit delivers power in an A/B configuration, meaning if one power input fails, it can switch to another within the unit.
These UPS modules can supply eight minutes of power to the data hall at a full load of six megawatts, covering the time it takes for LD6 backup diesel generators to spin up and provide power to the halls.
The generators can provide 36 hours of power before they need re-fuelling. In the event of exceeding this timeframe, LD6 has fuel supplier contracts that can rapidly deliver the diesel needed to keep the generators generating electricity.
Equinix tests the backup system once a month to ensure it functions correctly.
Equinix expects to fill 80 percent of the data centre's capacity within four years, and predicts the cash flow of the LD6 to become positive within nine months. This rapid return on investment will likely see successors to LD6, featuring the same energy efficient cooling systems.
Equinix is not the only data centre company exploring the use of fresh air cooling. Recently V3 visited London2, Virtus's second data centre, which uses a similar indirect air cooling system.
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