When Harrods decided to relocate its data centre to the roof of its flagship department store, the usual problem of capacity was just one concern. Another key factor was the presence of a huge fish tank on the sales floor directly above one of its server rooms.

The IT infrastructure to support the company’s million square feet of retail space, 900 tills and 2,500 staff at its Knightsbridge HQ – plus its operations at Heathrow and Gatwick – has historically been centred in the building’s basement.

Consolidation projects in the last couple of years to enable IT to keep up with growing business demands (that included introduction of HP blade servers to replace end-of-life and legacy servers) have not prevented the two existing server rooms from reaching full capacity. And that challenge called for some lateral thinking.

Extension of the current facilities wasn’t really an option, says John Dilkes, network infrastructure and security manager, as each square foot of space in the department store is highly valuable. “In considering a new facility we had the problem that floor space within Harrods is at a premium for retail operations.”

There were also logistical considerations to be taken into account: “The geography of the store is not really conducive to building a new room [nearby], as there are physical access and height restrictions,” he says.

There was also a problem of water leakage. Separate from the threat of the fish tank, one of the two server rooms had flooded – twice.

The challenge was seen as an opportunity rather than a burden, says Dilkes: “We had the unique opportunity to redesign our data centre operations. We needed to design a facility that would address every conceivable issue and offer us the adaptability and flexibility to build our IT into the future for a 10 to 15 year useful operating life.”

The team settled on the idea of building a modular or ‘pod’ structure on Harrods’ roof, with the understanding that the data centre could be ‘demountable’ if there was reason to move it to a new location. “This is obviously not something you would want to do but in principle it is possible,” says Vincenzo Bianco, technology controller at Harrods.

Before building could commence there were several physical issues to be ironed out. Firstly, an existing structure – the contractors’ canteen – had to be removed. Then a survey of the roof concluded that the main building’s supporting pillars needed strengthening. And lastly, steel girders were strung across the top of the building to carry the considerable weight of the data centre and its equipment.

 Fully assembled, the pod provides Harrods with a server room of 73.2 square metres, 10 square metres of plant room and 25.3 square metres of related office space.

The design and installation process took only three months and migration began in May. The most critical applications will be moved into the new server room first, principally the company’s SAP business systems. “For SAP we need to move 1.5 terabytes of data and the maximum window [of downtime] we can accept is six hours,” explains Bianco. It is likely that the operation will take place on a Sunday morning after the night jobs have been completed.

“Once we have moved SAP, the remaining machines can be moved in an easier way. We still need to pay attention but we have a longer downtime window which we can use for this migration,” says Bianco.

Bianco and his team are also nowlooking at ways to ensure the environment’s integrity. Power and cooling equipment from APC has been selected to provide the network-critical physical infrastructure, with APC partner Universal Power Systems handling the work.

Disaster recovery is also a key goal, with the eventual aim of replicating much of the infrastructure at a remote location. “Now what we want to achieve is to replicate the data in a different location – in a different building, in a different area.” Before serious plans can be laid however, the infrastructure team need to measure the bandwidth that they need. “One objective is to complete this by the end of the year so we can propose to the business for next year’s budget the investment to replicate remotely the same infrastructure.”