When AI Stumbles: Lessons from Real-World Inference Failures

Author: Denis Avetisyan


A detailed analysis of production incidents reveals critical vulnerabilities and practical strategies for building more reliable AI services.

The distribution of incidents reveals a correlation between model modality and severity, suggesting that certain approaches are disproportionately associated with more critical failures.
The distribution of incidents reveals a correlation between model modality and severity, suggesting that certain approaches are disproportionately associated with more critical failures.

This research presents an empirical study of high-severity incidents in a large-scale language model serving system, identifying failure modes and effective mitigation strategies for improved infrastructure resilience.

Despite the increasing reliance on large language models (LLMs), ensuring the reliability of their production deployments remains a significant challenge. This is addressed in ‘Enhancing reliability in AI inference services: An empirical study on real production incidents’, which presents a practice-based analysis of over 150 high-severity incidents in a hyperscale LLM serving system. Our study reveals that inference engine failures—particularly timeouts—dominate these incidents, yet a substantial portion are mitigated through automated responses or operational adjustments, highlighting opportunities for proactive resilience. Can systematic incident analysis and taxonomy development become a cornerstone of cost-efficient and dependable LLM service delivery at scale?


The Inevitable Cascade: Understanding Production Incidents

Modern IT operations face increasing challenges from incidents that impact service reliability and user experience. These disruptions, ranging from performance degradation to complete outages, cause user frustration and financial losses. The complexity of distributed systems and rapid software deployment exacerbate these issues.

Traditional incident response is reactive, focusing on mitigation after occurrence. While effective for restoration, this approach fails to address systemic weaknesses, leading to recurring incidents and wasted engineering resources. True stability requires a proactive stance, prioritizing root cause analysis.

Incident frequency varies considerably with severity, indicating a concentration of occurrences at specific levels of impact.
Incident frequency varies considerably with severity, indicating a concentration of occurrences at specific levels of impact.

By analyzing failure patterns, organizations can improve system resilience. This requires robust monitoring, automated diagnostics, and a culture of learning from failures – transforming incidents into opportunities for continuous improvement. The pursuit of stability isn’t about eliminating error, but about predictably containing its influence.

From Reaction to Prevention: A Taxonomy of Failure

A robust incident taxonomy is fundamental to effective root cause analysis, providing a structured framework for understanding system failures. Validation confirms the effectiveness of a four-way taxonomy for consistent incident classification.

Postmortem analysis, utilizing this taxonomy, systematically investigates incidents, identifying underlying causes beyond immediate symptoms. Analysis reveals that inference engine failures account for 60% of high-severity incidents, model configuration errors for 16%, and infrastructure failures for 20%.

The distribution of incidents differs across model families and severity levels, suggesting potential variations in reliability or error profiles.
The distribution of incidents differs across model families and severity levels, suggesting potential variations in reliability or error profiles.

By identifying recurring patterns, teams can transition from reacting to preventing incidents. This requires resilient systems and robust monitoring to detect and mitigate failures before they impact users.

Automated Resilience: The Logic of Self-Preservation

Monitoring systems are essential for maintaining IT infrastructure health, providing real-time visibility into potential issues. These systems collect metrics on resource utilization, application response times, and error rates, enabling rapid problem identification and resolution. Effective monitoring underpins proactive incident management and service optimization.

AIOps extends monitoring by applying artificial intelligence and machine learning to analyze operational data, enabling anomaly detection, failure prediction, and automated remediation. AIOps correlates events, reducing alert fatigue and improving root cause analysis.

Failover to different endpoints demonstrably improves service level agreements, highlighting the effectiveness of redundancy in maintaining performance.
Failover to different endpoints demonstrably improves service level agreements, highlighting the effectiveness of redundancy in maintaining performance.

Automated failover, driven by health probes, ensures continuous availability even during component failures. Capacity planning, informed by monitoring data and AIOps, proactively allocates resources to meet demand, preventing bottlenecks and optimizing service delivery.

LLM Operations: Constraining the Infinite

Deploying large language models (LLMs) presents distinct operational challenges: managing GPU capacity, handling long-running inference requests, and maintaining connection liveness. Effective solutions require resource orchestration and robust error handling.

LLM serving performance depends on configurable parameters. Tokenization strategies and sampling parameters significantly influence both quality and latency. Continuous monitoring and adaptive tuning are essential for optimization.

The large language model serving architecture illustrates a system designed for efficient and scalable deployment of advanced AI capabilities.
The large language model serving architecture illustrates a system designed for efficient and scalable deployment of advanced AI capabilities.

Service Level Objectives (SLOs) are paramount for measuring LLM-powered application reliability and performance. A recent study demonstrated that approximately 74% of high-severity incidents were auto-detected and resolved through operational actions, not code changes. Automated detection demonstrated high reliability (Cohen’s Kappa of 0.89). Proactive monitoring, automated failover, and intelligent capacity planning are crucial for both availability and responsiveness.

The successful operation of these complex systems isn’t merely about achieving functionality, but about forging a continuous, self-correcting equilibrium – a testament to the inherent stability found within rigorously defined constraints.

The pursuit of reliability in LLM serving, as detailed in the study of production incidents, echoes a fundamental mathematical principle. When considering the scale of these systems and the inevitable emergence of failures – from infrastructure vulnerabilities to model biases – one is compelled to ask: let N approach infinity – what remains invariant? Blaise Pascal offered insight with this quote: “All of humanity’s problems stem from man’s inability to sit quietly in a room alone.” In the context of AIOps and incident analysis, this speaks to the necessity of isolating root causes – stripping away cascading failures and complex interactions to reveal the core, unchanging element responsible for the disruption. The study’s failure taxonomy exemplifies this principle, aiming to identify the invariant characteristics of incidents despite varying conditions and scales.

Beyond Pragmatism: Charting a Course for Robust Inference

The presented analysis, while grounded in the pragmatic realities of production LLM serving, subtly underscores a persistent tension. Incident mitigation, frequently reliant on heuristics and reactive scaling, addresses symptoms, not inherent fragility. The taxonomy of failures, though valuable, remains descriptive; a formal, mathematically rigorous characterization of failure modes—identifying the minimal set of conditions leading to instability—remains conspicuously absent. Such a characterization would permit not merely faster response, but provable guarantees of resilience, a concept currently relegated to aspiration.

Future work should therefore prioritize the development of verifiable properties for LLM serving infrastructure. The field frequently celebrates ‘scalability’ as an end in itself, yet scale amplifies the impact of even minor, previously masked defects. A focus on correctness—on ensuring that the system behaves as defined, rather than simply ‘well enough’ under typical load—is paramount. The observed reliance on human intervention in resolving incidents is not a feature, but an admission of insufficient algorithmic robustness.

Ultimately, the pursuit of reliability must move beyond empirical observation and embrace formal methods. While monitoring and automated scaling offer temporary relief, they are compromises, not virtues. The true measure of progress will not be a reduction in incident frequency, but the elimination of entire classes of failures through provably correct system design.


Original article: https://arxiv.org/pdf/2511.07424.pdf

Contact the author: https://www.linkedin.com/in/avetisyan/

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2025-11-12 13:53