📅 November 4, 2026 • Blocks and Files
Inside xAI Colossus 2 - five data centers and a 1.2 million GPU target
The layout
Per Blocks and Files, Colossus 2 is a cluster of five data centers east of the Mississippi River in the Memphis and Southaven area, named Macrohard, Macroharder, Minihard, GunRange and Spam. Training runs on Macroharder, Minihard and GunRange, with roughly 220 thousand Nvidia GB200 nodes per site and an 800G network fabric at each. GunRange is expected online before the end of November.
Inference tier
The Spam site is planned for inference with about 200 thousand GB300 nodes, targeting launch before the end of December 2026.
Storage
Per the report, the sites likely run VAST Data and DDN storage with aggregate capacity at the exabyte level. Dataset staging, checkpoint writes and checkpoint restart are the traffic profile that defines this tier.
IMPACT
The practical takeaway is architectural. At this scale training and inference are separated into dedicated sites with different hardware - GB200 nodes for training with 800G fabrics per node, GB300 nodes serving live inference traffic. Network bandwidth per node is the binding constraint for synchronizing tens of thousands of nodes during large runs, and storage is engineered as a first-class subsystem where checkpointing and dataset staging sit on exabyte-class VAST Data and DDN platforms. The stated total, about 1.2 million Blackwell GPUs by the end of 2026, would make this one of the largest single compute campuses on record. For capacity planners the report reads as a reference design - five specialized sites, a network fabric per workload class and storage sized for training-state management. The sequencing also matters for capacity planning - GunRange coming online in late November adds a third training site first, then the Spam inference tier lands before the end of December, so the campus ramps in two distinct steps rather than one. All GPU counters are estimates per Blocks and Files, built from open data and satellite imagery rather than official disclosure.
Sources: blocksandfiles.com
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