The X2, developed under the code name Black Widow, was originally expected to be a standalone supercomputer system, superseding the Cray X1 parallel vector supercomputer.
However, the X2 was eventually launched as one of the four processor "blade" options for the XT5h system.
An X2 blade comprises two nodes, each with four symmetric multiprocessing vector processors and 32 or 64 GB of shared memory.
X2 processors are connected using a radix-64 "fat-tree" interconnect implemented by the YARC router ASIC.
The X2 processor nodes integrate with the Cray XT5h's UNICOS/lc OS, user environment, and storage subsystem, as part of the Rainier project.