Brocade Communications Systems caused a small stir with some slides shown at its Spring Analyst Day presentation. One slide showed that a 384-port Brocade 48000 (48K) Director uses less power than an unpopulated Cisco Systems' MDS 9513 Multilayer Director (956 volt-amps vs. 1,060 volt-amps, respectively). A second slide showed the same 384-port 48K director pitted against a configured MDS 9513 director (956 volt-amps vs. 2,704 volt-amps, respectively). Both companies staunchly defend their power metrics and claim they offer the more efficient product.
Cisco contests the slide comparing the populated 48K to an empty MDS 9513. "We certainly dispute these numbers because they just don't make sense," says Rajeev Bhardwaj, Cisco's director of product management, data center business unit. "When customers deploy [a] SAN, they connect switches together, they put servers, they put storage and, of course, they enable all the advanced intelligent functions," he says. "We have to look at real-world solutions."
Mario Blandini, Brocade's director of product marketing, says that particular slide is included to put perspective on the power efficiency built into Brocade's system. "You would never buy an empty system from someone else and compare it to a full system from someone else," he says.
Measuring watts/port is a better measurement, says Cisco. Its tests show that an MDS 9513 consumes 5.1 watts/port while Brocade's 48K consumes 5.8 watts/port. In addition, Cisco maintains that only half of the 48K's 384 ports can be used to maintain high availability and that more features are built onto its line card, so power is used more efficiently. "We consume less power and do more," says Bhardwaj.
Brocade refutes Cisco's claims that only half the ports can be used and that the 9513 card carries more features. "They are simply wrong," John Oram, product marketing manager at Brocade, writes in an email. "If we pulled a CP [control processor], all 384 ports would still be available." Further, Oram says the 48K line card has functionality similar to that of Cisco's. "We have functionality as much if not more [than Cisco's card]," he notes.
But a debate about how much power one director uses vs. another seems a relatively marginal one. SAN directors, combined with all other communication devices, take up only approximately 15% of the power consumption in a data center, according to a study conducted by Dell in the summer of 2006.
Users should decide for themselves which power metric they'll require vendors to use in their proposals. "It's really whatever the customer has it plugged into, then takes the measurements, that will determine the advantage or disadvantage," says Brian Babineau, senior analyst at Enterprise Strategy Group, Milford, MA.