SAN JOSE, Calif. – AT&T will stop buying systems next year that don't conform to new policies about air cooling and it is starting a move to liquid cooling. The decisions mark a new milestone in how rising use of mobile data and video is creating power and heat issues in data centers and central offices.
"In 2012 AT&T and Verizon will no longer accept equipment with side-to-side airflow," said Bon Pipkin, a network engineering manager at AT&T, speaking in a keynote at the Advanced TCA Summit here.
"Most [carrier] facilities are designed for 30-50W per square foot so a seven-foot rack should not draw more than 850W—but that’s one circuit board in a next-generation ATCA chassis, and we are already exceeding our standards," said Pipkin.
To keep pace with rising network demands, "our company is moving to distributed refrigerant cooling [DRC], and for both airflow and DRC we want to partner with manufacturers right now," said Pipkin. "This is a major change for AT&T, and we are also taking to Verizon about moving in this direction," he said.
The move to use of some form of refrigeration comes as some big data center operators are moving away from air condition and adopting ambient air. Facebook, for example, announced last week it is opening its first European data center in Sweden, in part to use ambient air and save power sand cost by eliminating air conditioning.
AT&T will publish a document next year describing its new thinking about cooling the more than 7,000 central office facilities it currently manages. "We will ask vendors to price an optional DRC, and we have talked to half a dozen vendors about this already," Pipkin said.
The document will state a requirement that vendors who use side-to-side air flow provide mechanical workarounds such as ducts and snorkels to conform to AT&T's front-to-rear cooling approach.
The speech marked the first time a carrier said it would not purchase equipment unless it conforms to a specific cooling approach, said one veteran of the ten-year old ATCA standard who asked not to be named.
Vendors will listen, given AT&T's purchasing clout. But they are concerned that "if everyone chooses a different air-flow plan, you lose efficacy," the ATCA engineer said. In addition, a transition to liquid cooling "might be nasty, lots of people have to learn lots of new skills," he added.
A variety of liquid and state-change cooling systems have been deployed or tested, linking to systems in a host of ways. AT&T was not specific about what kind of refrigerant it will use, but Pipkin did give some examples of how the AT&T cooling systems might be deployed.
The requirements come as the PICMG group that defines the ATCA chassis and board standards is well along on work on next-generation extensions. They are expected to be complete sometime in 2012 and define boards that draw up to 800W in a double-sided chassis generally optimized for front-to-rear or bottom-to-top air cooling,
In a separate speech yesterday, a Huawei engineering manager called for standards defining liquid-cooled systems in 2015 using boards that could draw up to 1,000W. Today's ATCA boards typically draw 200-300W.
Vendors selling moderate-sized ATCA systems are likely to face some conflicts with the new AT&T requirements, the ATCA expert said. Systems using six or fewer boards typically lay the boards horizontally and use side-to-side air cooling to minimize space—another big requirement from carriers.
In a Q&A session, Pipkin said he realizes carriers create difficulties by asking for systems with more performance, better thermals and lower acoustics. "It's a game of whack a-mole, and we realize that," he said.
Currently ATCA standards are being widely adopted by carriers for use in systems that process network and mobile data. The standard is expected to be adopted by a growing sector of high-end video processing systems.
At peak periods, video represents as much as a third of all Internet traffic, said one engineering manager from Cisco Systems, in a separate talk here.