The Altix 4000 is Silicon Graphics' current Itanium-based product line. It is composed of two models, the Altix 450, a mid-range server, and the Altix 4700, a high-end server.
An Altix 4700 system can contain up to 2048 dual-core Itanium 2 and Itanium ("Montvale" revision) microprocessor sockets, which are connected by the NUMAlink 4 interconnect in a fat tree network topology. The microprocessors are accompanied by up to 128 TB of memory (192TB with single microprocessor socket blades and 16GB DIMMs).
These systems are based on nodes contained within a blade that plugs into an enclosure, the individual rack unit (IRU). The IRU is a 10U enclosure that contains the necessary components to support the blades such as the power supplies, two router boards (one for every five blades) and a L1 controller. Each IRU can support ten single-wide blades or two double-wide blades and eight single-width blades. The IRUs are mounted in 42U-high rack, and each rack supports up to four IRUs.
There are two types of node, processor and memory, which are contained within a blade. Compute blades contain a processor node and consist of two PAC611 sockets for Itanium 2 and Itanium microprocessors, a Super-Hub (SHub) application-specific integrated circuit (ASIC) (chipset) and eight dual in-line memory module (DIMM) slots for memory. The number of microprocessor sockets in a compute blade is one or two. One-processor socket configurations provide more bandwidth as only one microprocessor socket is using the front side bus and local memory. Two-processor socket configurations do not support hyperthreading. Memory blades are used to expand the amount of memory without increasing the number of processors. They contain a SHub ASIC and 12 DIMM slots. Both compute and memory blades support 1, 2 4, 8, and 16 GB DIMMs. SGI support does not currently support any installations with 16GB DIMMs.
Multiple servers in configurations described above can be combined on the same Numalink fabric up to the theoretical maximum of 8,192 nodes (16,384 OS cpus).
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