Nemotron-3 30B-A3B — Warm-Start SFT 200k (instruct)

A instruct SFT of nvidia/NVIDIA-Nemotron-3-Nano-30B-A3B-BF16 on the geodesic-research/sft-warm-start-200k dataset (subset no_think, ~259M tokens, single epoch).

This is one of four canonical warm-start baselines for the Geodesic Research SFM / inoculation campaigns. Models trained with this checkpoint as the starting point should be directly comparable across the {30B, 120B} × {think, instruct} matrix.

Variant

instruct — uses the geodesic-research/nemotron-instruct-tokenizer, whose chat template never auto-injects <think>...</think> reasoning tags. Inference produces direct instruct-style responses without reasoning traces..

The encoder is byte-identical to the upstream nvidia/NVIDIA-Nemotron-3-Nano-30B-A3B-BF16 tokenizer; only the chat template differs from upstream.

Training data

  • HF dataset: geodesic-research/sft-warm-start-200k
  • Subset: no_think
  • Examples: 200,000 chat-format conversations (no held-out validation/test split)
  • Tokens: 259M (counted with the instruct tokenizer)
  • Sequence packing: pad_seq_to_mult=1, pad_to_max_length=false, packed sequence length 8192

Training recipe

Hardware Isambard GH200, 8 nodes × 4 GPUs (sm_90, BF16)
Parallelism TP=2, EP=2, PP=4, CP=1
Data parallelism DP_pure=4, grad_accum=16
Global batch size 64 (× 8192 tokens = 524k tokens/batch)
Sequence length 8192
Optimizer distributed Adam (β1=0.9, β2=0.95, ε=1e-8, wd=0.1, clip=1)
Learning rate 5e-06 (cosine decay to 0, 5% warmup)
Precision BF16
Iterations 495 (≈ 1 epoch over the dataset)
W&B run link

Evaluation

Smoke / quick / full suites via sfm-evals.

Suite What Sample count W&B group
Coherence qualitative 8-prompt generation 8 link
Smoke 5-sample sanity check across alignment + capability 5/task link
Quick alignment + capability sweep 100 (mostly) link
Full paper-default sample counts across alignment + capability varies link

Coherence: empty response rate = 0.0% on the 8-prompt diverse-instruction set (temperature=1.0, max_new_tokens=3000).

For reproducible eval runs:

cd /lus/lfs1aip2/projects/public/a5k/repos/sfm-evals
ISAMBARD_TP=1 just submit-quick-all-isambard geodesic-research/nemotron_30b_warm_start_sft_200k_instruct
ISAMBARD_TP=1 just submit-full-all-isambard geodesic-research/nemotron_30b_warm_start_sft_200k_instruct

Limitations

  • SFT checkpoint converted with --not-strict: the upstream Nemotron-3 Multi-Token-Prediction (MTP) head weights are randomly initialized, since SFT training does not update them. MTP is not used during standard generation, so this does not affect normal inference.
  • Trained on a single epoch of 200k chat-format examples — narrower coverage than the upstream NVIDIA instruct release.

License

Inherits the NVIDIA Open Model License from the base model nvidia/NVIDIA-Nemotron-3-Nano-30B-A3B-BF16.

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