arXiv:2608.07226 · v2
Dual-Node NVIDIA DGX Spark over Tailscale: A Remote-Access Testbed for Distributed LLM Training and Cyber-Threat-Intelligence Fine-Tuning
摘要
Practical evidence for multi-node training on desktop-class accelerators remains limited. This report presents a proof-of-concept deployment of distributed NanoChat pretraining across two NVIDIA DGX Spark systems, each with a GB10 Grace Blackwell system-on-chip and 128 GB of unified memory, administered remotely over a Tailscale mesh VPN and connected for training by a dedicated 200 Gb/s QSFP56 direct fiber link. PyTorch torchrun, DDP, and NCCL were configured with one process per node, a depth-20 NanoChat model, a device batch of 32 sequences per node, a 2,048-token context, and eight gradient-accumulation steps, giving 1,048,576 tokens per optimizer step for the 896.5-million-parameter model. The run took 4,980 steps over about four days, averaging 63.4 s of measured training time per step (about 16,540 tokens/s) and processing about 5.22 billion tokens. We document link configuration, container setup, interface binding, a step-zero evaluation bug that triggered NCCL timeouts, checkpointing, and troubleshooting lessons. We also built a cybersecurity fine-tuning dataset from 77 CISA advisories (338 training, 37 validation conversations) and compared a baseline SFT checkpoint against a CTI-augmented checkpoint on 17 held-out prompts with an Ollama-hosted LLM judge: CTI-specific categories improved while general-knowledge categories regressed, for a small overall change from 2.06 to 2.29 on a 0-10 scale. Version 2 adds a stage-2 fine-tune with a MITRE ATT&CK technique dictionary under a deterministic evaluation: in-dictionary ID-to-name lookup reaches 98.5%, yet none of 50 held-out IDs is named correctly, knowledge of held-out threat groups, software, campaigns, and vulnerabilities stays near zero, and general ability drops measurably. The study establishes feasibility rather than a scaling-efficiency claim.
作者备注：v2: corrects pretraining token and throughput figures, judge model, and SFT details; adds parameter count, software provenance, and a stage-2 ATT&CK-dictionary fine-tuning study. 17 pages, 5 figures, 6 tables. Deployment runbook and code: https://github.com/viyer-research/dual-dgx-spark-tailscale-testbed