Cooler Servers or Cooler Rooms?

mstansberry writes "Analysts, experts and engineers rumble over which is more important in curbing server heat issues; cooler rooms or cooler servers. And who will be the first vendor to bring water back into the data center?"

Comments

Cray still has water cooling!

[green pizza]

Unlike most companies that are considering going back to water cooling, Cray has always used water cooling for their big iron. In fact, the only air cooled Crays are the lower end or smaller configured systems.

All hail the Cray X1E !

Re:Cray still has water cooling!

[1zenerdiode]

I thought Cray's originally used Fluorinert(tm), which is definitely *not* water... *spark* *spark* *fizzle*

All hail non-conductive fluorochemicals!

Re:well I've always wondered this

[drinkypoo]

When you use DC power in a data center you run a high voltage (24V, 48V, depending on equipment) and then it's regulated down to all the usual voltages. However, it's a lot easier to transmit AC power over distances. It's not exceptionally lossy to convert AC to DC or vice versa any more.

Re:well I've always wondered this

[Detritus]

Due to the insane current and voltage regulation requirements of today's motherboards, the power supply for the CPU and associated chips has to be physically close and tightly integrated into the motherboard. You can't just pipe in regulated DC voltages from an external power supply directly to the chips on the motherboard. In your typical PC, the power supply (the metal box) provides bulk regulated DC power. Some stuff can run directly from the power supply. Components with demanding power requirements, like the CPU, are powered by dc-to-dc converters on the motherboard. These take DC power from the power supply, convert it to high-frequency AC, and back to regulated DC.

The general rule is that stricter requirements for power supply performance can only be met by decreasing the physical distance between the power supply and the load. The trend towards lower supply voltages and higher currents makes the problem worse.

AC power wiring is cheap and well understood. It doesn't require huge buss bars or custom components. It is the most economical way to distribute electrical energy.

Once you reach the box level, you want to convert the AC to low-voltage DC. Confining the high-voltage AC to the power supply means that the rest of the box doesn't have to deal with the electrical safety issues associated with high-voltage AC. The wiring between the power supply and load is short enough to provide decent quality DC power at a reasonable cost. Those components that require higher quality power can use the DC power from the power supply as the energy source for local dc-to-dc converters.

You could feed the box with -48 VDC like the telephone company does with its hardware. You would still end up with about the same amount of hardware inside the box to provide all of the regulated DC voltages needed to make it work. Cost would increase because of the lower production volumes associated with non-standard power supplies.

In the end, it boils down to economics. DC power distribution costs more money and it doesn't meet the performance requirements of modern hardware. The days of racks full of relays, powered directly from battery banks, are long gone.

and that voltage loss = ?

[SuperBanana]

This means that if you produce regulated 5V at one side of your datacentre, by the time it's reached the other side it's not 5V any more. But it should be easy to get round this by producing 6V and having DC regulators; they're very small and extremely efficient these days.

...aaaaaand where do you think that energy goes?

[DING] "Heat, Alex" "Correct, for $100."

...aaaaaand what do you think that energy loss thanks to high current means?

[DING] "Efficiency less than a modern AC->DC power supply" "Correct, for $200."

Anyone particpating in the "DC versus AC" discussion would do well to pick up a history book and read about Westinghouse and Edison. There's a reason we use A/C everywhere except for very short hauls. Modern switching power supplies are very efficient and still the best choice for this sort of stuff.

Water-chilled Cabinets Already In Use for Blades

[miller60]

Liebert and Sanmina have been selling blade server cabinets that use chilled water for at least three years. Vendors and data center operators have been wrestling with the heat loads generated by blade servers since 2001, and the dilemma of how to cool high-density "hot spots" has caused many tech companies to wait on buying blades to replace their larger servers. That's changing now, driven by the need to save costs with more efficient use of data center space.

The industry has taken a two-pronged approach. Equipment vendors have been developing cabinets with built-in cooling, while design consultants try to reconfigure raised-floor data center space to circulate air more efficiently. The problem usually isn't cooling the air, but directing the cooled air through the cabinet properly.

There was an excellent discussion of this problem last year at Data Center World in Las Vegas. As enterprises finally start to consolidate servers and adopt blade serves (which were overhyped for years), many are finding their data centers simply aren't designed to handle the "hot spots" created by cabinets chock full of blades. Facilities with lower ceilings are particularly difficult to reconfigure. The additional cooling demand usually means higher raised floors, which leaves less space to properly recirculate the air above the cabinets. Some data center engineers refer to this as "irreversibility" - data center design problems that can't be corrected in the physical space available. This was less of an issue a few years back, when there was tons of decent quality data center space available for a song from bankrupt telcos and colo companies. But companies who built their own data centers just before blades became the rage are finding this a problem.