So, how can an SP be configured? There can be 4 to 16 processors per frame (or cabinet) and 1 to 16 frames per system. Frames can consist of BOTH thin and wide nodes. The main difference between thin and wide nodes is that generally wide nodes have the capacity for larger memory and a larger memory cache. Standard SP2 systems could contain up to 256 nodes. Up to 512 nodes can be ordered from IBM by special request. (ORNL has a 16 node SP2, Maui has a 400 node SP2, and Cornell has a 512 node machine.) An optional high performance switch (HPS) for inter-processor communication is usually included on most systems. Such a switch can interconnect up to 16 nodes with up to 16 other nodes. This high performance switch has a 40 MB/sec peak bi-directional bandwidth. More than one HPS may be included when the number of nodes in the SP2 machine is greater than 32.
The IBM SP2 is fairly robust in that it has concurrent maintenance, which simply means each processor node can be removed, repaired, and rebooted without interrupting operations on other nodes.