This guide explains how to identify and resolve sudden latency increases in running services by collecting key metrics, focusing on GC behavior, thread and lock analysis, CPU and system resources, and using diagnostic tools such as jstat, jstack, and distributed tracing.
The article reveals the hidden gap between textbook Kubernetes knowledge and real production failures, offering six practical skills—from interpreting pod symptoms and debugging without logs to capacity planning and treating events as first‑class signals—essential for engineers to survive on‑call crises that interview questions never cover.
When a service crashes and users flood you with complaints, following a structured 15‑minute workflow—first narrowing the impact, then probing six layers (network, system, application, data, external services, security), and finally documenting the incident—lets you pinpoint and fix most outages quickly and reliably.
This article walks through how packet loss can occur at any layer of the Linux network stack, demonstrates using ethtool, netstat, iptables, tc and tcpdump to locate the issue, and shows how adjusting MTU and removing a netem rule fully resolves the problem.
When a colleague struggles with a 2 GB log file, the author demonstrates how to combine tail, less, grep, sed, and awk commands to quickly locate errors, extract time windows, count occurrences, and analyze traffic, turning cumbersome log inspection into an efficient, repeatable workflow.
A client reported sudden Oracle database slowdown, prompting a post‑mortem analysis using AWR and TFA data that revealed GC bottlenecks, RAC heartbeat packet loss, and an intermittent storage link failure, ultimately resolved by disabling the faulty port and restarting the affected node.
Learn how to efficiently locate and analyze Java exceptions and other errors in real-time by combining tail, grep, zgrep, and advanced command-line options, enabling complete stack traces, context preservation, compressed log handling, trend analysis, and performance optimization for faster root-cause identification.
A production migration from Oracle to OceanBase caused a column‑length change to trigger offline DDL, leading to connection errors, INSERT latency spikes, and complete table blockage; the article reproduces the fault, analyzes the OMS conversion and OceanBase DDL rules, and provides a two‑step remediation and a method to verify online DDL execution.
This article explains how the Domain Name System (DNS) converts human‑readable website names into IP addresses, details the four‑layer caching hierarchy, compares recursive and iterative query modes, outlines common DNS failures, and provides practical steps to troubleshoot and accelerate DNS resolution.
The article explains how inode exhaustion on Linux filesystems can cause "No space left on device" errors despite available disk space, details inode structure and allocation, provides step‑by‑step diagnostics, monitoring scripts, best‑practice recommendations, and recovery procedures to prevent and resolve inode‑related issues.
When a server’s CPU suddenly hits 100%, this guide shows how to quickly identify the offending process, use tools like top, perf, strace, vmstat, and iostat for deep analysis, set up monitoring and alerts, plan capacity, and apply code and system optimizations to prevent future spikes.
A step‑by‑step guide shows how to use Linux commands like top, vmstat, free, iostat, and ss to quickly identify CPU overload, memory pressure, disk I/O bottlenecks, and network port problems, providing a practical cheat sheet for effective server troubleshooting.
A senior engineer recounts a midnight e‑commerce promotion disaster caused by a mis‑designed cache‑update loop, detailing the alert storm, step‑by‑step investigation, JVM heap and GC analysis, the offending FastJSON serialization code, the rapid rollback, and three hard‑won operational rules.
This article walks through the complete DHCP process—from a device’s initial broadcast for an IP address, through server offers, request, and acknowledgment—while also covering static versus dynamic IP configuration, lease management, and common troubleshooting scenarios such as missing addresses and IP conflicts.
This comprehensive guide walks you through the seven key performance metrics, resource, application, and system component indicators, and provides step‑by‑step methods, advanced tips, and tool recommendations for diagnosing and resolving Kubernetes performance bottlenecks from cluster‑wide to pod‑level details.
This guide explains why Docker pull commands often timeout in China due to outdated foreign registries, lists common invalid mirror configurations, provides three verified mirror URLs for 2025, and walks through editing the daemon.json file, restarting Docker, and testing the setup, while sharing practical troubleshooting lessons.
When a production pod suddenly hit 90% CPU and dozens of young and full GCs within two hours, the author walks through a step‑by‑step investigation using top, thread‑level monitoring, jstack, and stack analysis to pinpoint a Java‑level memory issue and resolve it.
The article explains why Docker image pulls often time out in China due to outdated or unreachable registry mirrors, lists common invalid mirror configurations, and provides three verified mirror URLs for 2025 together with step‑by‑step setup instructions and practical troubleshooting tips.
This article walks through Easysearch’s built‑in CCR feature, explaining why cross‑cluster replication is needed, how to set up two single‑node clusters locally, configure security, create a leader index, start replication, monitor status, and avoid common pitfalls.
Horizontal Pod Autoscaler (HPA) in Kubernetes automatically scales pod replicas based on metrics like CPU, memory, or custom indicators, and this guide explains its core principles, configuration pitfalls, step‑by‑step troubleshooting commands, and advanced considerations such as API versions, stabilization windows, and integration with Cluster Autoscaler.
This guide walks you through a complete, step‑by‑step process for identifying why MySQL CPU usage jumps to 100%, from initial symptom verification and data‑flow analysis to locating slow queries, killing them, optimizing SQL, adding indexes, and setting up monitoring and alerts to prevent recurrence.
This guide presents the most common operations interview questions—covering Linux mounting, filesystem issues, server performance, networking fundamentals, RAID, load balancing, and web server configuration—along with detailed, high‑scoring answers that showcase systematic thinking, troubleshooting logic, and production‑grade awareness.
When servers become sluggish, fail to start, or run out of disk space, blindly restarting only masks the problem; this guide compiles ten critical Linux commands with usage scenarios to help you quickly pinpoint CPU, memory, port, disk, swap, and network issues for effective troubleshooting.
This guide provides a step‑by‑step troubleshooting workflow for Spring Boot microservices using Nacos as a configuration and service registry and MySQL as the database, covering log inspection, process verification, port checks, network tests, configuration validation, database connectivity, system resources, startup commands, and an optional diagnostic script.
After adding an HTTPS certificate to an Nginx site, browsers load the page fine but curl requests are reset; this article walks through network tests, configuration tweaks, packet captures, and the eventual discovery that enabling ssl_session_cache resolves the issue.
Linux system administrators often encounter diverse failures, and this guide compiles over 40 distinct fault types—including system, network, hardware, and software issues—offering practical troubleshooting steps to help engineers quickly diagnose and resolve problems while building a solid knowledge base.
After adding an HTTPS certificate to an Nginx server, browsers load the site fine but curl requests are reset; the article walks through network checks, cipher and buffer tweaks, a certificate swap, and ultimately shows that configuring the ssl_session_cache directive resolves the reset issue.
This guide explains essential Linux memory metrics, demonstrates how to use tools like free, top, vmstat, sar, and ps, and outlines a systematic, layered approach to pinpointing and resolving memory problems, including cache analysis and leak detection.
This comprehensive guide walks you through troubleshooting PostgreSQL physical (stream) replication, covering environment prerequisites, anti‑pattern warnings, step‑by‑step diagnostics for replication lag, split‑brain scenarios, replication slot problems, monitoring setup with Prometheus, and best‑practice recommendations to keep your primary‑standby cluster healthy.
This guide provides a step‑by‑step troubleshooting workflow for common Spring Boot microservice issues involving Nacos and MySQL, covering log inspection, process verification, port checks, network connectivity, configuration validation, database connection tests, resource monitoring, and a one‑click diagnostic script.
Linux DNS goes far beyond simple name‑to‑IP translation, involving hierarchical resolution, caching, and modern components like systemd‑resolved; this guide explains core concepts, the full lookup process, essential configuration files, and practical best‑practice steps such as reliable resolvers, cache management, DNSSEC, encrypted transport, and diagnostic tools.
This guide walks you through the most frequent Kubernetes problems—from image pull failures and CrashLoopBackOff to DNS, storage, node readiness, and RBAC errors—providing clear diagnosis steps, essential kubectl commands, and concrete solutions to keep your clusters healthy.
This guide walks through Kubernetes pod lifecycle phases, container states, restart policies, health‑check probes, lifecycle hooks, init containers, common troubleshooting scenarios, and best‑practice recommendations, providing concrete YAML examples and kubectl commands to help operators manage pods from creation to graceful termination.
This guide explains why HBase may fail to connect to Zookeeper in distributed storage environments and provides step‑by‑step troubleshooting, including service checks, configuration validation, network testing, log analysis, version compatibility, service restarts, and Java code examples with retry logic.
This guide systematically outlines the typical Nginx error codes, missing client IP, WebSocket proxy failures, load‑balancing issues, static file problems, large upload limits, SSL/TLS errors, cache misses, and rate‑limiting, providing root‑cause analysis, step‑by‑step checks, configuration fixes and useful command‑line tools.
Learn a step‑by‑step Linux CPU high‑usage diagnostic guide covering ten root causes, quick monitoring commands, deep analysis with top, ps, strace, perf, and flamegraphs, plus practical remediation and long‑term monitoring setup using sar and Prometheus to prevent future spikes.
This guide provides a systematic Linux performance troubleshooting cheat sheet covering CPU, memory, disk I/O, network, processes, system calls, logs, and kernel parameters, complete with over 20 practical commands, real‑world case studies, best‑practice checklists, and an FAQ to help ops engineers quickly pinpoint and resolve performance bottlenecks.
When Kubernetes deployments fail, most issues stem from misconfigurations, image problems, or resource constraints, and this guide explains the ten most frequent errors, detailed troubleshooting commands, a generic debugging framework, and proactive practices to prevent future failures.
This article details Bilibili's implementation of a large‑language‑model‑driven intelligent assistant that helps engineers diagnose and resolve massive offline and real‑time data‑processing failures, describing the platform’s five‑layer architecture, common failure and slowdown causes, and the need for AI‑powered troubleshooting support.
This article provides a comprehensive, step‑by‑step checklist for diagnosing and resolving Nginx 502 Bad Gateway errors, covering backend service verification, configuration checks, log analysis, resource monitoring, network troubleshooting, special scenarios, and long‑term preventive measures.
A sudden Redis memory surge from 2 GB to 20 GB was traced to a misconfigured list-compress-depth parameter, revealing how uncompressed lists and queue backlogs can cause ten‑fold memory growth, and outlining step‑by‑step diagnostics, compression fixes, and long‑term optimization strategies.
This article presents a complete, step‑by‑step method for reducing average Kubernetes fault‑diagnosis time from half an hour to under three minutes, covering the root causes of slow manual debugging, a one‑click diagnostic script, efficient kubectl shortcuts, visual tools, log aggregation, automated response workflows, and real‑world case studies.
This article dives into advanced Kubernetes troubleshooting techniques, covering persistent volume claim pending errors, event and audit log analysis, dashboard deployment, health probes, temporary containers, and node‑level debugging to help DevOps engineers resolve complex cluster issues efficiently.
Learn how to configure and diagnose Linux network issues using essential commands such as ifconfig, ping, traceroute, netstat, ss, dig, nslookup, route, ethtool, and arp, with practical examples and a systematic troubleshooting workflow to quickly identify and resolve connectivity problems.
This guide provides a step‑by‑step troubleshooting workflow for Spring Boot microservices using Nacos as a config/registry and MySQL as the database, covering log inspection, process checks, port listening, network connectivity, configuration validation, database connectivity, system resources, startup commands, and an optional one‑click diagnostic script.
This guide explains why SSH agent forwarding can break despite correct client and server settings, reveals the hidden role of connection multiplexing, and provides a step‑by‑step solution to reset the master connection so forwarding works again.
This article walks you through ten real-world Nginx failure cases—covering 502 errors, SSL expiration, high concurrency bottlenecks, cache misconfigurations, log rotation issues, load‑balancing mistakes, security gaps, reverse‑proxy quirks, URL rewrite conflicts, and monitoring—while teaching a systematic diagnostic methodology for ops engineers.
Learn comprehensive DNS troubleshooting from fundamental symptoms to advanced debugging tools, scripts, and performance optimization, with real‑world case studies and step‑by‑step guidance for handling DNS failures in traditional, containerized, and enterprise environments.
This comprehensive guide dissects every stage of the Kubernetes Pod lifecycle, explains underlying mechanisms, and equips operators with practical debugging commands, scripts, and best‑practice configurations to swiftly resolve common production issues such as pending pods, crash loops, slow startups, and network failures.
This comprehensive guide walks you through Linux routing fundamentals, static and dynamic route configuration, policy routing, IP forwarding, NAT, troubleshooting, performance tuning, security hardening, and container networking, equipping operations engineers with the skills to design, optimize, and secure complex network infrastructures.
This guide presents twelve practical grep command-line patterns—including case‑insensitive search, line‑number highlighting, keyword counting, multi‑keyword regex, context display, real‑time filtering, and integration with find—each illustrated with exact syntax and brief explanations to help Linux administrators and developers troubleshoot logs more efficiently.
This guide walks through fixing Performance plugin incompatibility, adjusting Jenkins CSP security, customizing access paths, handling git clone timeouts, fixing batch command failures, updating vulnerable jars, running JNLP files on Windows nodes, disabling CSRF, tuning JVM memory, and optimizing disk usage to keep Jenkins stable and efficient.
This comprehensive guide walks you through SELinux fundamentals, core concepts, mode differences, security contexts, real‑world configuration examples for web and database services, boolean management, troubleshooting techniques, performance tuning, and enterprise‑grade best practices to turn SELinux into a reliable production‑level security guardian.
This free Ceph operations manual outlines common administrative tasks, troubleshooting techniques, and advanced topics, providing storage engineers with a comprehensive reference for managing, monitoring, and optimizing Ceph clusters in production environments.
This article walks through a real‑world case where HTTPS requests made with curl are reset on an Nginx server, detailing the step‑by‑step investigation, configuration tweaks—including client buffers and SSL session cache—and the final resolution that restores successful connections.
This guide explains why a server may fail telnet connections despite opened security policies, and provides step‑by‑step commands to restart the polkit service, reload networking, and flush and re‑activate the network interface to restore proper connectivity.
When a Kubernetes cluster suddenly fails to respond with an x509 certificate expiration error, this guide walks you through using kubeadm commands to renew all certificates, update kubeconfig files, restart kubelet, and verify the new expiration dates, ensuring the cluster returns to normal operation.
This guide introduces tcpdump, a powerful network packet capture tool, explains its filtering capabilities with logical operators, and provides numerous practical examples—from capturing traffic on specific interfaces and hosts to filtering by ports, protocols, and saving captures—helping users troubleshoot network issues efficiently.
This comprehensive guide shares a veteran ops engineer's real‑world troubleshooting mindset, the SEAL framework, a curated toolbox of monitoring, logging, performance, and network utilities, detailed case studies, incident‑response grading, automation scripts, and future‑ready AIOps practices for keeping production systems stable.
This comprehensive guide teaches Linux operations engineers advanced command‑line techniques, powerful one‑liners, and step‑by‑step troubleshooting for common errors, enabling faster issue resolution, higher efficiency, and proactive system maintenance.
This article provides a systematic, step‑by‑step methodology for identifying the root causes of Redis performance degradation—including big keys, slow queries, expiration spikes, memory limits, fork latency, AOF flushing, memory fragmentation, swap usage, huge pages, and CPU binding—and offers immediate mitigation tactics as well as long‑term architectural solutions to restore and maintain high throughput.
When Kafka backs up and Logstash fails to write to Elasticsearch with a 403 cluster_block_exception, the index is locked by a write block, which can be resolved by clearing the index.blocks.write setting via the Elasticsearch API or Kibana dev tools.
The article recounts a series of three OOM incidents in a production service that combines Paimon data lake and RocksDB via an SDK, detailing the step‑by‑step investigation, the discovery of excessive bucket‑driven thread creation and off‑heap memory leaks, and the final mitigation measures that restored stability.
This guide introduces tcpdump, a powerful network packet capture tool, explaining its basic usage, filtering options, interface selection, logical expressions, and advanced examples such as capturing specific hosts, ports, protocols, limiting packet counts, and saving captures to files for detailed analysis.
This guide walks you through a step‑by‑step process for identifying the root cause of sudden 100% CPU usage on AWS RDS MySQL instances using Performance Insights, SHOW FULL PROCESSLIST, and Performance Schema, and provides practical tips for remediation.
This guide explains the most common Linux VPS performance problems—CPU overload, memory exhaustion, and disk I/O bottlenecks—and provides step‑by‑step commands and optimization techniques to monitor, troubleshoot, and resolve them efficiently.
This article compares Logstash 9.x with previous releases, shows a working 9.x configuration, explains why root execution is blocked, details the deprecation of the cacert setting in favor of ssl_certificate_authorities, and provides step‑by‑step troubleshooting tips—including permission checks and the --config.test_and_exit flag—to resolve typical startup and data‑ingestion issues.
This guide explains AWS CloudFormation fundamentals, including Stacks, StackSets, Outputs, and Exports, and provides step‑by‑step troubleshooting techniques for common deployment failures such as secret rotation errors.
This article introduces the most important Linux network testing utilities—covering basic connectivity, routing analysis, DNS resolution, port monitoring, bandwidth measurement, and packet capture—providing a comprehensive guide that helps operations engineers diagnose and resolve network issues ten times faster.
This article explains why traditional Linux monitoring tools often miss deep kernel issues and shows how to use eBPF‑based utilities such as biolatency, runqlat, and offcputime to pinpoint CPU, I/O, and lock‑contention problems with concrete command examples and a practical troubleshooting workflow.
This article explains why MySQL 5.7 community edition may block online DDL operations when leftover temporary table files remain, analyzes the root cause, and provides step‑by‑step commands and alternative solutions to safely remove the orphaned tables.
This guide introduces Ceph as a leading open‑source distributed storage solution, explains why enterprises choose it for scalable data platforms, and provides a comprehensive operations manual covering common tasks, troubleshooting, and advanced management to help storage engineers efficiently run Ceph clusters.
This article walks through troubleshooting a failed deployment caused by a full disk, showing how to use df -h to check overall disk usage and various du options (including --max-depth and -sh) to pinpoint large directories and resolve the issue.
Learn how to systematically diagnose and resolve Nginx failures in cloud‑native deployments by understanding core concepts, applying a step‑by‑step algorithm, analyzing logs, configurations, and system metrics, and using practical Kubernetes examples, code snippets, and performance models to ensure reliable service operation.
This article walks through a systematic Linux network packet‑loss investigation, covering every protocol layer from the NIC to the application, analyzing ethtool, netstat, tc, iptables rules, MTU settings, and finally applying fixes to restore reliable connectivity.
Learn step‑by‑step how to troubleshoot MySQL master‑slave replication problems, from verifying component roles and executing the correct SHOW SLAVE STATUS command inside the MySQL client, to fixing missing command errors, checking IO/SQL threads, and restarting replication in Docker‑based environments.
This guide provides a comprehensive, step‑by‑step troubleshooting checklist for Kubernetes operations, covering Pod, Node, and cluster‑level problems, common pod status anomalies, and container exit‑code analysis to help operators quickly locate and resolve issues.
This article introduces Ceph as a leading open‑source distributed storage solution and presents a comprehensive operations manual covering common tasks, fault handling, and advanced topics to help engineers efficiently manage and troubleshoot Ceph clusters.
Learn how to leverage IntelliJ IDEA's powerful debugging features—including step commands, conditional breakpoints, thread inspection, and expression evaluation—plus troubleshoot common startup errors and automatically generate serialVersionUID, providing essential techniques for Java developers to debug efficiently and resolve IDE issues.
This guide outlines a step‑by‑step method to diagnose and release MySQL table locks by checking open tables, inspecting running processes, querying InnoDB transaction and lock tables, and generating KILL statements to terminate blocking sessions.
This tutorial walks you through downloading Docker Desktop, enabling required Windows features like Hyper‑V and Containers, applying Chinese localization, configuring firewall and hosts settings, and troubleshooting common errors with detailed PowerShell commands and configuration files.
This article walks through the background, reproduction steps, investigation methods, and concrete solution for MySQL metadata lock (MDL) issues that cause DDL statements to hang, and provides practical tips to prevent similar lock problems in production environments.
When a midnight CPU alarm threatened service availability, I walked through rapid system checks, JVM profiling, algorithm refactoring, database indexing, Docker isolation, and Prometheus alerting to bring CPU usage back below 30% and restore millisecond‑level response times.
A seasoned desktop support veteran shares the untold struggles, quirky philosophies, time‑saving calculations, and memorable incidents that reveal how sysadmins silently keep an organization running while juggling endless reboot debates, hardware mysteries, and unexpected human drama.
This article explains why many consider embedded development difficult, then walks through systematic steps for reproducing, locating, analyzing, and resolving typical embedded bugs—including logging, online debugging, version rollback, binary commenting, register snapshots, and regression testing—to help engineers troubleshoot effectively.
This article explains how to troubleshoot and resolve the MySQL "Too many connections" error by using GDB to modify the max_connections parameter on a running MySQL 5.7 instance without restarting, including step‑by‑step commands, sysbench load testing, and two practical methods.
This article compiles the ten most common MySQL error scenarios—from connection limits and replication conflicts to installation failures, password resets, truncate side‑effects, configuration pitfalls, charset issues, binlog formats, timeout problems, and file‑handle limits—offering clear diagnostic steps and concrete commands to resolve each case.
This comprehensive guide explains Loki's lightweight log aggregation architecture, compares it with ELK, details AllInOne, Helm, Kubernetes, and bare‑metal deployment methods, shows Promtail and Logstash integration, and provides practical troubleshooting tips for common issues.
This article compiles twenty frequent operational incidents—from server inaccessibility and database connection errors to disk‑space exhaustion, high CPU usage, memory leaks, network latency, DNS failures, service crashes, file‑system corruption, update problems, permission misconfigurations, web‑server and email issues, backup failures, load‑balancing anomalies, firewall rule mistakes, SSH connection problems, database performance degradation, dependency gaps, and virtual‑machine faults—detailing their symptoms, step‑by‑step troubleshooting procedures, and concrete remediation actions.
This article examines a recurring Kubernetes issue where a node becomes NotReady for exactly three minutes after a kubelet restart, explains the underlying PLEG and node‑status mechanisms, and offers a free, in‑depth Kubernetes handbook for further study.
This article explains how to find the MySQL deadlock log, parse its contents to determine the time, order, and affected rows, identify the lock types and root cause, and provides extended examples of special locking scenarios, all illustrated with real‑world SQL and code snippets.
The article explains why the Java JVM throws java.lang.OutOfMemoryError: Unable to create new native threads, outlines common causes such as thread leaks, insufficient RAM, other processes, and kernel limits, and provides practical solutions and troubleshooting steps to resolve the issue.
This article analyzes six common MySQL query performance traps—type conversion, function usage, left‑most prefix, implicit charset conversion, left‑most match, and optimizer mis‑selection—illustrates each with real‑world SQL examples, explains why they degrade performance, and provides concrete remediation steps and verification tools.
This guide explains what Prometheus monitoring is, walks through downloading the correct version for a Kubernetes cluster, customizing alert rules, deploying and cleaning up Prometheus, and troubleshooting common Alertmanager connection problems by checking DNS and network configurations.
This guide explains how to install Erlang, download and compile RabbitMQ 3.0.4, start the server in detached mode, verify its status, and troubleshoot common issues such as port conflicts on CentOS 6, providing complete command‑line instructions and configuration tips.
During a New Year holiday, an Oracle database suffered severe hangs due to a GC buffer busy acquire wait event caused by a faulty heartbeat network cable, leading to index unusable errors and extensive troubleshooting steps that reveal common causes and preventive measures.
This article outlines the most important Linux log files under /var/log, explains what each records—from system and kernel messages to authentication, web server, database, and firewall events—and shows practical commands for inspecting them, helping SREs improve fault detection and system observability.
This article walks through a step‑by‑step troubleshooting process for JVM Out‑Of‑Memory (OOM) incidents, covering symptom identification, monitoring tools like top, jstat, and jmap, root‑cause analysis, and actionable recommendations to prevent future memory leaks.
This article explains common Kubernetes DNS resolution failures, both for external domains and internal service discovery addresses, and provides a step‑by‑step troubleshooting workflow that includes checking CoreDNS, examining resolv.conf, adjusting DNS settings, and recreating CoreDNS when necessary.
This guide explains common Kubernetes DNS problems—including failure to resolve external domains, inter‑pod service discovery addresses, and related impacts on applications like Nginx reverse proxies—and provides step‑by‑step troubleshooting procedures such as checking CoreDNS, inspecting resolv.conf, and customizing dnsPolicy and dnsConfig in pod specifications.
