Incident Postmortems & Architecture Studies

Real-world failure autopsies, cascading outage analyses, and enterprise architectural studies dissecting GPU memory fragmentation, RL optimization collapse, and throughput bottlenecks with peer-verified remediations.

Technical Studies8

SEV-1 Failure Autopsies2

Enterprise Cases6

Verified Outcomes100%

All Case Studies (8)Incident Postmortems (2)Enterprise Architectures (6)

SEV-1 Critical Outage

Reinforcement Learning & Reasoning Model Alignment

16 min read

Incident Postmortem: Reasoning Collapse and Zero-Variance Optimization Divergence in RL Fine-Tuning

An in-depth postmortem analyzing optimization divergence, runaway thinking loops, and zero-variance gradient explosions during large-scale GRPO reasoning alignment.

Blast Radius & System Impact:

64x H100 cluster halted · Policy loss NaN · Rollout ceiling 16k tokens

Root Cause & Failure Mode:

Division by zero in group advantage normalization during uniform rollout failure (std(R) = 0)

Architectural Remediation:

Zero-variance clamp guard (std(R) < ε => A=0) · Token generation budget caps · Format penalty

Verified 29 Sep 2026Read Full Postmortem

SEV-1 Critical Outage

High-Throughput Model Serving & GPU Memory Management

16 min read

Incident Postmortem: High-Concurrency KV-Cache Memory Fragmentation in Production LLM Serving

An architectural autopsy of a tier-1 LLM cluster cascading failure: how non-contiguous block fragmentation in PagedAttention triggered out-of-core thrashing and 100x P99 latency degradation.

Blast Radius & System Impact:

34,210 requests stalled · 102.3x P99 TPOT spike (18.4s) · 1,200 concurrent sessions

Root Cause & Failure Mode:

Non-contiguous block tail internal fragmentation combined with default host swap triggering PCIe bus thrashing

Architectural Remediation:

Zero host swap (--swap-space 0) · Chunked prefill co-scheduling · Radix prefix caching

Verified 29 Sep 2026Read Full Postmortem