Silicon Graphics - High-end Server Market

High-end Server Market

SGI continued to enhance its line of servers (including some supercomputers) based on the SN architecture. SN, for Scalable Node, is a technology developed by SGI in the mid-1990s that uses cache-coherent non-uniform memory access (cc-NUMA). In an SN system, processors, memory, and a bus- and memory-controller are coupled together into an entity called a node, usually on a single circuit board. Nodes are connected by a high-speed interconnect called NUMAlink (originally branded CrayLink). There is no internal bus, and instead access between processors, memory, and I/O devices is done through a switched fabric of links and routers.

Thanks to the cache coherence of the distributed shared memory, SN systems scale along several axes at once: as CPU count increases, so does memory capacity, I/O capacity, and system bisection bandwidth. This allows the combined memory of all the nodes to be accessed under a single OS image using standard shared-memory synchronization methods. This makes an SN system far easier to program and able to achieve higher sustained-to-peak performance than non-cache-coherent systems like conventional clusters or massively parallel computers which require applications code to be written (or re-written) to do explicit message-passing communication between their nodes.

The first SN system, known as SN-0, was released in 1996 under the product name Origin 2000. Based on the MIPS R10000 processor, it scaled from 2 to 128 processors and a smaller version, the Origin 200 (SN-00), scaled from 1 to 4. Later enhancements enabled systems of as large as 512 processors.

The second generation system, originally called SN-1 but later SN-MIPS, was released in July 2000, as the Origin 3000. It scaled from 4 to 512 processors, and 1,024-processor configurations were delivered by special order to some customers. A smaller, less scalable implementation followed, called Origin 300.

In November 2002, SGI announced a repackaging of its SN system, under the name Origin 3900. It quadrupled the processor area density of the SN-MIPS system, from 32 up to 128 processors per rack while moving to a "fat tree" interconnect topology.

In January 2003, SGI announced a variant of the SN platform called the Altix 3000 (internally called SN-IA). It used Intel Itanium 2 processors and ran the Linux operating system kernel. At the time it was released, it was the world's most scalable Linux-based computer, supporting up to 64 processors in a single system node. Nodes could be connected using the same NUMAlink technology to form what SGI predictably termed "superclusters".

In February 2004, SGI announced general support for 128 processor nodes to be followed by 256 and 512 processor versions that year.

In April 2004, SGI announced the sale of its Alias software business for approximately $57 million.

In October 2004, SGI built the supercomputer Columbia, which broke the world record for computer speed, for the NASA Ames Research Center. It was a cluster of 20 Altix supercomputers each with 512 Intel Itanium 2 processors running Linux, and achieved sustained speed of 42.7 trillion floating-point operations per second (teraflops), easily topping Japan's famed Earth Simulator's record of 35.86 teraflops. (A week later, IBM's upgraded Blue Gene/L clocked in at 70.7 teraflops).

In July 2006, SGI announced an SGI Altix 4700 system with 1,024 processors and 4 TB of memory running a single Linux system image.