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네이버 클라우드 GPU 인스턴스 DDP 랑데부 멈춤 및 VPC MTU 병목 진단

기본 MTU 제한으로 인한 VPC 서브넷 패킷 단편화, 비공개 보조 인터페이스 바인딩 실패, torchrun 마스터 주소 해석 오류를 명확히 분리합니다.

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네이버 클라우드 멀티노드 분산 학습 로그 분석

Upload your log file. Review the selected evidence and masking, then run diagnosis. Keep the original log for any follow-up questions.

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training_logs.txt

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Up to 50 diagnoses a day for 30 days. Verify your work email to activate an eligible company evaluation, then replay a resolved incident and compare the evidence and next steps with your team's confirmed cause.

What a useful evaluation should establish

단순 타임아웃 오류 메시지 이면에 숨겨진 VPC 네트워크 구성 및 방화벽 규칙 문제를 신속하게 파악합니다.

Use Denpex alongside your existing telemetry tools to investigate submitted incident evidence. With monitoring configured on a supported plan, detected failures can trigger alerts and an automatic diagnosis from the captured evidence.

Inside Denpex

See the evidence, not just the claim

Follow the causal chain, inspect the quoted evidence and prepare the next handoff. These actual product captures use founder-account examples and the VS Code extension, with the source identified under each image. Open a capture to inspect it at full size.

Denpex founder-account example: a causal graph connects an Xid 48 ECC event to a rank exit and downstream collective failures, with quoted evidence for each stage. — Live founder-account capture from the bundled NCCL/ECC example. Follow the hardware event, rank exit and downstream symptoms with a supporting log quote at each stage.Inspect original image

Denpex hardware handoff summary asks the operator to capture diagnostic evidence and verify RMA eligibility with the vendor. — Actual hardware handoff summary from the same founder-account example. Capture diagnostic evidence before an approved reset, then confirm RMA eligibility with the vendor.Inspect original image

Denpex historical example says a collective timeout does not establish the initiating rank, cause or failure domain and requests distinguishing evidence before a remedy. — Founder-account example restored from history. The original timeout remains unattributed, and the UI keeps the missing-evidence assessment visible.Inspect original image

Denpex VS Code extension displaying a bundled OOM-before-NCCL example, matched log evidence, verification guidance and an investigation handoff. — Actual VS Code extension capture of the bundled OOM-before-NCCL example. Review matched log evidence, verification guidance and the investigation handoff without leaving the editor.Inspect original image

Failure Signature Triage

네이버 클라우드 플랫폼 - Observed Runtime Evidence

네이버 클라우드 플랫폼 GPU 가이드

Incident pattern summary

네이버 클라우드 VPC 환경에서 2개 이상의 노드로 학습을 시작할 때, 초기 TCPStore 연결 후 대용량 텐서 동기화에서 멈추는 현상을 점검하여 VPC MTU 및 NCCL_SOCKET_IFNAME 설정을 최적화합니다.

Terminal traceback excerpt (네이버 클라우드 플랫폼)

[W 2026-10-28 03:15:44.112831 88120 init.py:738] NCCL info: opType 2 (ALLGATHER) timeout, local rank 0, peer ranks [1, 2, 3]
[ERROR] [Socket] Connection refused to 10.0.2.14:29500 (VPC security group / routing check required)
terminate called recursively