As servers get more powerful and dense, selling space in a co-location facility is becoming a bigger challenge than ever. The chief culprits are blade servers and their attendant high-density storage racks, says Philip Cheek, the European MD of managed services company and ISP Globix.

"We saw the need for higher densities 18 months ago," he adds. "Organisations like ours can't just sell space anymore. In the past, we would allow the customer to do their own configuration - now we need cold and hot aisles, so we provide the racks and tell them how to configure them. There is best-practice now for data centre set-up.

"We never used to monitor kit coming in and out, but now we have to, both for security and for power consumption," he adds. "We can't have people bringing blades and so on into standard cabinets.

"The standard is 2kW per rack, and the average per unit is more like 1.25kW, but the problem is that some abuse it and bring in 2.5kW, and if you don't manage that, you can't fulfil your obligations because others have taken the headroom."

Yet Cheek says that Globix has also discovered how to turn density into a commercial advantage, thanks to its decision to install self-contained server racks with their own built-in cooling alongside the standard equipment racks at its City of London hosting centre.

"We have started charging clients on their power-draw rather than physical space," he says. "That has driven us towards the ability to create a denser environment. Space is still a cost to us though, so if we can create a denser area, it should also be better for us."

Sealed boxes
Supplied by APC - Cheek says it was "the most advanced" of the three vendors Globix talked to - the new denser racks are in effect sealed boxes, each with its own air conditioner that extracts the heat generated inside and pipes it out, in this case up to a chiller on the roof of the building. Globix has two types: mid-density units capable of handling 7kW per rack, and high-density versions with a 15kW capacity.

According to Cheek, it all comes down to economics: even though the APC boxes cost more, once the equipment is dense enough to get 7kW of servers into a single rack, it is cheaper for his clients to do that than buy three or four standard racks.

Of course, from the customer's perspective, this is in large part down to how Globix prices each cabinet type - a 7kW box costs less than three times as much to rent as a 2kW box, and a 15kW box is only about 50 percent more expensive than 7kW. But Philip Cheek stresses that there are direct advantages for Globix too.

"Some other ISPs throw space at the problem and part-populate cabinets instead," he says. "Our infrastructure is over-engineered, so high density is a better use of our space.

"The rationale is it drives a better return per square foot, but it's opportunist too because there are clients that need it. It's also maybe 30 to 40 percent cheaper for the client to buy one big cabinet instead of four or five standard ones."

Blades at the cutting edge
The equipment inside the APC units is mostly blade technology - blade servers and rack storage. As to who's using this type of technology, Cheek says his customers range from small dotcoms to big enterprises, and offers the example of a pharmaceutical research company which has four racks of IBM blade servers hosted with him, taking around 64kW in total.

Having dealt with server density for now, other problems are emerging of course. Weight is a new one, with load-spreaders already needed beneath some of the equipment in the City data centre. "The company's next expansion will be in the basement - on the upper floor it's already hitting the floor loading limits," Cheek says.

The next major bottleneck though will be the availability of enough electricity - there's enough backup power from a pair of 2MW generators at the City site, but even so, one of the seven 15kW units is lying empty until the company can get more mains power in.

Philip Cheek adds that this is also why Globix will not be deploying high-density racks at its hosting centre in London's West End. That site does not have enough backup generator capacity, and it's not worth upgrading it when there is high-density hosting space available not far away.

"The take-up of blades has been a case of finding clients or ISPs that can house them - that's not simple," he adds. "It's not taken the natural 'everything gets smaller' course of mobile phones, say."

Who's making money on the Net?
It also means Globix has to be more inventive in what services it offers and to whom, he says.

"We want clients to buy single high-density cabinets - for large numbers of cabs, it's more cost effective for them to do it internally. But fewer people now are able to generate the revenue to pay £2500 per [15kW] rack. To be here it has to be ecommerce or something else that's mission-critical. Some sites just cannot afford to be down.

"The people who make money out of the Net are e-retailers, gambling and betting. The holiday side is massive now - although even eBookers takes less than 50 percent of its bookings online - and then you have the adult industry.

"Gambling organisations, once they're established, never make a loss. The serious money goes on just before a race as gamblers court the odds, so they need guaranteed up-time, checks that the site is up, DDoS blocking..."

Looking forward, he says power needs in the data centre can only grow: "We will build out with an average of 4kW per cab, rather than 2kW - we're limited a bit for space, but power is the problem.

"Companies like APC and Liebert are working on up to 25kW per cabinet, and there is technology out there that could require 35 to 40kW in that much space. If you can't find anywhere to do that, there's no point deploying it."