Distributed Training at Scale: FSDP, Tensor and Pipeline Parallelism

Mixed-precision Adam costs 16 bytes per parameter, so a 70B model needs 1120 GB of state before a single activation is stored. Getting that onto real hardware, and keeping the run alive while a component fails every three hours, is the skill behind every frontier model. This path builds it: where the memory actually goes, how ZeRO and FSDP shard what data parallelism duplicates, how tensor and pipeline parallelism split the computation itself, and what makes a fifty-day run finish.