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Soaking your servers to keep them cool is not a new concept. Cray was doing it way back in the 1980s with the Cray-2. Wikipedia tells us that its use of liquid cooling led to the Cray-2 being given the nickname Bubbles, and to gags including "No Fishing" signs, cardboard depictions of the Loch Ness Monster rising out of the heat exchanger tank, plastic fish inside the exchanger.
I suspect that Iceotope, which has spent eight years developing a new form of immersive liquid cooling for servers, won't give rise to such levity. We're much more serious about this stuff now. Ahem.
Iceotope's CTO and founder Peter Hopton recently took me through the system which he claimed can save half of your datacentre energy costs.
The company sells cabinets of modules containing Supermicro server motherboards and all the parts that constitute a server, apart from spinning hard disks. "In the module are hot-swap, leakless water connectors that go into water backplane," Hopton said. "You never see water."
Each module is a server is encased in a leak-proof box filled with 3M's Novec 7300. On heating, this inert liquid expands 10 times more than water and so generates convection currents that carry the heat away, aided by a chimney effect created by the internal shape of the box. It convects very fast – up to 6 cm/sec according to Hopton -- and is less viscous with a lower surface tension than water, which enables it to reach the parts that water might not.
The module has a large bore water channel within a second compartment which forms a heat transfer plate. It plugs into a backplane which connects it to a closed-loop water system that includes a pair of redundant heat exchangers. Hopton said that the heat transfer plate inside the module was designed using principles of CFD to maximise convection. Water passed through the heat exchangers’ building sides can then exhaust heat into the outside world.
The advantages of Iceotope's system are that liquid is obviously much more efficient at heat dispersal than air -- water is about 3,000 times better, for example -- and that needs only a 72W pump to drive the water, which eliminates all the chilling equipment normally found in a datacentre. Additionally, the system cools all the server's components, not just the CPU and chipset.
Of course the downside is getting over the idea of filling your datacentre with liquid, to which point Hopton said:
"If it leaks, all the water will sit at the bottom of the cabinet in a tray as there's not much of it. You already have water in the datacentre in the CRAC and the humidifiers, so all we have done is brought the water a bit closer to the servers."
For Hopton, this system changes the economics of the datacentre: "There's no dust or air filtration, no chillers, no special rooms, and it's noiseless, you could put it in a library. Since our servers are protected from the atmosphere they should be more reliable, with no thermal stresses. In future, server complexes could be dirty with a concrete floor, since they're all sealed units."
Iceotope's biggest hurdle is of course the incumbents. It would be a big bet to shift to a new server design from a single, unknown vendor, let alone redesign your datacentre so radically.
Hopton is conscious of this: "Our long term goal is to build a licensing model in which other people make server units and we work with them, but we have to stimulate the market first and demonstrate there is a market for them before IBM etc will take note.
"So that's what we're doing. We will start being a customer of a board maker and build servers but then we will want global cabinet and server makers selling them through their own channels. We want to encourage diversity."
Ultimately, the cash will speak. Hopton claims that datacentre energy running costs could be cut by 50 percent, and that Iceotope servers can be much more tightly packed, as they don't need fans or space for air to circulate.
And to prove that it works, he cites a Swiss bank which has installed Iceotope servers.
"In future, you will buy a server from someone else and we are talking to server makers," Hopton said. "Right now we want to get into the commodity server market, and we can do that at a reasonable price point."
16 March 2012