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Small Tree brings InfiniBand to Apple Xserve G5 clusters

Small Tree Communications, a Minnesota firm that makes networking products for Apple servers, has taken the plunge into the InfiniBand market. InfiniBand, a type of low-latency network, is primarily used for supercomputing clusters, where its speed gives it an edge over Ethernet.

For Small Tree, which has repeatedly introduced new Ethernet-based products to the Apple market, the product represents a new direction.

“We were getting requests from Apple and some of Apple’s customers for someone with experience in supercomputers, which we have, to build suport for the Mac,” said Corky Seeber, the company’s CEO.

Seeber said Ethernet “is more of a data-passing protocol ... but it doesn’t happen with the latency that allows you to bring two computers working on the same problem at the same time.”

InfiniBand works by providing multiple channels over which data can flow, then giving exclusive use of a full channel to each communication between devices on the network. That means data sent over a single wire doesn’t have to be routed between multiple devices, which requires extra processing overhead.
In January, Small Tree approached Mellanox, which produces the network hardware and wanted to open up the Apple market. The two companies collaborated to bring InfiniBand to the Mac. Seeber said he saw government, academic and private-sector opportunities, and his company may try to crack the video editing market, where increased use of computer-generated effects in movies has led to intense demands on processing power.

Small Tree has already worked with Virginia Tech on its System X supercomputer, located at the Terascale Computing Facility. The facility's director, Srinidhi Varadarajan, said the system is used in the computational sciences and engineering, which require high-performance communications.

But Seeber said the technology would become important for anyone doing high-volume calculations. “I believe [InfiniBand] is going to expand into other areas ... I think it’s fair to say that it’s going to be more than just supercomputing,” he said.

Ohio State University has helped Small Tree fine-tune its performance, collaborating with the company to benchmark its performance and coordinate it with the open-source version of OSU's Message Passing Interface for the Xserve G5, called MVAPICH.

"We are seeing excellent stability and performance with Small Tree's [InfiniBand] driver," said D.K. Panda, a professor with OSU's Network-Based Computing Laboratory. "For 2.0 gigahertz G5 systems, we consistently record MPI-level one-way latency of 6.1 microseconds and unidirectional bandwidth of 931 million bytes per second with MVAPICH 0.9.4 version."

Now that he has brought a number of networking firsts to the Apple platform, Seeber said he is not that worried about competition intruding on the niche Small Tree has carved out, because Apple's market share is small enough that "people tend to say, 'There's just not enough market for two or three people.'"

This could change, but for now, Small Tree's primary competition remains networking on non-Apple platforms, which make up a large installed base. While Seeber thinks that Apple Xserves are very competitive and are attracting more users, there is a certain momentum built up among other platforms.

"Once you have a few million dollars in infrastructure built up, you don't want to hear that the stuff you don't have is really cool," Seeber said.

Jason Stitt is WTN's associate editor and can be reached at

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