Page 29 - GCN, May 2017

EMERGING TECH
BY PATRICK MARSHALL
Making cool, cable-free data centers possible via laser data transmission
TELL A DATA CENTER MANAGER that you have a way to get rid of the tangle of wiring that connects racks of servers and you’ll likely see his or her eyes go wide. Then add that your solution will also slash the cost of keeping the data center cool and you’ll likely hear cries of “Hallelujah!”
FireFly — an infrared laser transmission sys-
tem being developed by researchers at Penn State University, Carnegie Mellon University and Stony Brook University with support from the National Science Foundation — just might be the technology that evokes that response.
Yes, FireFly — which stands for Free-space opti- cal Inter-Rack nEtwork with high FLexibilitY — bends the rules for generating compelling acronyms, but it’s unlikely data managers will mind.
In the proof-of-concept system, the researchers have demonstrated that infrared lasers can be used to send bidirectional data streams — in this case,
a television transmission
— at 10 gigabits/sec each way. A receiver captures the infrared transmission and conveys it to a fiber-optic cable on the other end, which delivers the data to
a server.
In a real-world imple-
mentation, the laser transmitters and receivers would be attached to the tops of server racks because the system requires a direct line-of-sight connection. The transmitter device is equipped with tiny mirrors that can quickly be adjusted
What’s more, tests of
the system showed that it could deliver the data at high speed and with an extremely low error rate, making it suitable for fault- intolerant applications. In fact, according to Kavehrad, initial tests resulted in no
ble of handling many en- vironmental effects, such as transient obstacles, misalignments and scintil- lation,” Kavehrad said.
Data managers will no doubt be happy enough about eliminating the massive amounts of wiring that currently tangle data centers, but Kavehrad said FireFly will also greatly reduce the amount of elec- tricity required to power them.
Much of the energy
data centers draw is used to power racks with idle servers that can’t be shut down because they’re physically wired to servers in use. With FireFly, how- ever, the ease of rerouting data traffic means that idle or underused servers can be shut down.
“In comparison to clas- sic wired infrastructure, FireFly...deployment and maintenance \[are\] faster and simpler, and it offers dynamic configuration of the network,” Kavehrad said.
“Moreover, FireFly links can be used to augment the performance of virtu- alization techniques that allow load balancing.”
He added that recent testing indicates that as much as 33 percent of data center energy costs could be saved by using FireFly. •
An infrared laser beam travels into the receiver of a proof-of- concept system that has demonstrated high-speed, nearly error- free data delivery.
to target different receiv- ers connected to different servers.
“A laser can be recon- figured to aim at different targets as a network switch routes traffic bursts of thou- sands of data packets,” said Mohsen Kavehrad, profes- sor of electrical engineering at Penn State. Just as on
a shooting range, he said, “you aim \[at\] the target and shoot, then turn and shoot the next target.”
errors at all; the team had to decrease power to gener- ate errors.
Although the system’s rack-to-rack capabilities have been demonstrated, Kavehrad said the team wants to eventually elimi- nate the need for fiber- optic connections between the receivers and servers by integrating Airy beam lasers, which do not have a line-of-sight requirement.
“These \[lasers\] are capa-
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PATRICK MANSELL/PENN STATE UNIVERSITY