SGI Origin 2000

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The SGI Origin 2000, code named Lego, is a family of mid-range and high-end servers developed and manufactured by SGI, introduced in 1996 to succeed the SGI Challenge and POWER Challenge. At the time of introduction, these systems ran IRIX 6.4 and later, IRIX 6.5. A variant of the Origin 2000 with graphics capability is known as the Onyx2. An entry-level variant based on the same architecture but with a different hardware implementation is known as the Origin 200. The Origin 2000 was succeeded by the Origin 3000 in July 2000, and was discontinued on 30 June 2002.

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[edit] Models

  • Origin 2100 - 2 to 8 processors, 16 GB maximum memory, deskside chassis (not scalable)
  • Origin 2200 - 2 to 8 processors, 16 GB maximum memory, deskside chassis
  • Origin 2400 - 8 to 32 processors, 64 GB maximum memory, single rack chassis
  • Origin 2800 - 32 to 128 processors, 256 GB maximum memory, multi-rack chassis

[edit] Hardware description

The Origin 2000 is based on nodes that are plugged into a backplane. Each backplane forms a module that can contain four node boards, two router boards and twelve XIO options. The modules are then mounted inside a deskside enclosure or a rack. Deskside enclosures can only contain one module, while racks can contain two. In configurations with more than two modules, multiple racks are used.

[edit] Architecture

An Origin 2000 system is comprised of nodes linked together by an interconnection network. It uses the distributed shared memory S2MP (Scalable Shared-Memory Multiprocessing) architecture. The Origin 2000 uses NUMAlink (originally named CrayLink) for its system interconnect. The nodes are connected to router boards, which use NUMAlink cables to connect to other nodes through their routers. The NUMAlink's network topology is a bristled fat hypercube. In configurations with more than 64 processors, a hierarchical fat hypercube network topology is used instead. Additional NUMAlink cables, called Xpress links can be installed between unused Standard Router ports to reduce latency and increase bandwidth. Xpress links can only be used in systems that have 16 or 32 processors, as these are the only configurations with a network topology that enables unused ports to be used in such a way.

[edit] Router boards

There are four different router boards used by the Origin 2000. Each successive router board allows a larger amount of nodes to be connected.

[edit] Null Router

The Null Router connects two nodes in the same module. A system using the Null Router cannot be expanded as there are no external connectors.

[edit] Star Router

The Star Router can connect up to four nodes. It is always used in conjunction with a Standard Router to function correctly.

[edit] Standard Router (Rack Router)

The Standard Router can connect up to 32 nodes. It contains the SPIDER ASIC ASIC, which serves as a router for the NUMAlink network. The SPIDER ASIC has six ports, each with a pair of unidirectional links, connected to a crossbar which enables the ports to communicate with each other.

[edit] Meta Router (Cray Router)

The Meta Router is used in conjunction with Standard Routers to connect more than 32 nodes. It can connect up to 64 nodes.

[edit] Origin 2000 nodes

An Origin 2000 node fits on a single 16" by 11" printed circuit board that contains one or two processors, the main memory, the directory memory and the Hub ASIC. The node board plugs into the backplane through a 300-pad CPOP (Compression Pad-on-Pad) connector. The connector actually combines two connections, one to to the NUMAlink router network and another to the XIO I/O subsystem.

[edit] Processor

Each processor and their secondary cache is contained on a HIMM (Horizontal Inline Memory Module) daughter card that plugs into the node board. At the time of introduction, the Origin 2000 used the IP27 board, featuring one or two R10000 processors clocked at 180 MHz with 1 MB secondary cache(s). A high-end model with two 195 MHz R10000 processors with 4 MB secondary caches was also avaliable. In February 1998, the IP31 board was introduced with two 250 MHz R10000 processors with 4 MB secondary caches. Later, the IP31 board was upgraded to support two 300, 350 or 400 MHz R12000 processors. The 300 and 400 MHz models had 8 MB L2 caches, while the 350 MHz model had 4 MB L2 caches. Near the end of its life, a variant of the IP31 board that could utilize the 500 MHz R14000 with 8 MB L2 caches was made avaliable.

[edit] Main memory and directory memory

Each node board can support a maximum of 4 GB of memory through 16 DIMM slots by using proprietary ECC SDRAM DIMMs with capacities of 16, 32, 64 and 256 MB. Because the memory bus is 144 bits wide (128 bits for data and 16 bits for ECC), memory modules are inserted in pairs. Because the Origin 2000 uses a distributed shared memory model, directory memory, which contains information on the contents of remote caches, must be used in configurations with more than 32 processors. The directory memory is contained on proprietary DIMMs that are inserted into eight DIMM slots set aside for its use. In configurations where there are fewer than 32 processors, the directory memory is contained within the main memory.

[edit] Hub ASIC

The Hub ASIC interfaces the processors, memory and XIO to the NUMAlink#NUMAlink 2 system interconnect. The ASIC contains five major sections: the crossbar (XB), the I/O interface (II), the network interface (NI), the processor interface (PI) and the memory and directory interface (DM), which also serves as the memory controller. The interfaces communicate with each other via FIFO buffers that are connected to the crossbar. When two processors are connected to the Hub ASIC, the node does not behave in a SMP fashion. Instead, the two processors operate separately and their buses are multiplexed over the single processor interface. This was done to save pins on the Hub ASIC. The Hub ASIC is clocked at 100 MHz and contains 900,000 gates fabricated in a five-layer metal process.

[edit] I/O subsystem

The I/O subsystem is based around the Crossbow (Xbow) ASIC, which shares many similarities with the SPIDER ASIC. Since the Xbow ASIC is intended for use with the simpler XIO protocol, its hardware is also simpler, allowing the ASIC to feature eight ports, compared with the SPIDER ASIC's six ports. Two of the ports connect to the node boards, and the remaining six to XIO cards. While the I/O subsystem's native bus is XIO, PCI-X and VME64 buses can also be used, provided by XIO bridges.

A IO6 base I/O board is present in every system. It is a XIO card that provides:

[edit] See also

[edit] References