After a mistaken rm -rf command wiped an entire production server, I recovered critical MySQL data using ext3grep, extundelete, and binlog restoration, documenting the step‑by‑step process, scripts, and lessons learned to avoid similar disasters.
This article explains the comprehensive concept of high‑availability systems, covering redundancy, failover, consistency challenges, various technical solutions, SLA definitions, and the organizational and engineering practices required to achieve multiple “9s” of availability.
This guide walks you through obtaining a trusted SSL certificate, generating keys and CSR with OpenSSL, configuring HTTPS in Nginx, and applying performance and security enhancements such as keep‑alive, session caching, HSTS, strong cipher suites, and name‑based virtual host solutions.
This article presents the event‑driven architecture of a hotel order transaction system, outlines common challenges such as QMQ configuration, exception handling, and coupling, and introduces an Actor‑based solution that provides decoupling, customizable retry, fault‑recovery, and detailed monitoring for over twenty business services.
This article details a real‑world investigation of extremely low‑probability core dumps and memory leaks in a heavily modified Nginx/OpenSSL stack, covering debugging strategies, custom traffic‑control testing, distributed load generation, use of valgrind and AddressSanitizer, performance profiling with perf, and the mindset needed to solve such high‑concurrency bugs.
This article introduces ES2015 arrow functions, showing their concise syntax, how they differ from traditional function expressions, the implicit handling of the this context, and practical examples that eliminate the need for manual this binding, helping developers write cleaner JavaScript.
This article explains how enterprises can overcome manual deployment challenges by standardizing their tech stack, defining mutable and immutable deployment modes, designing an XY‑axis model for system components, and implementing continuous integration, delivery, feedback, and monitoring using tools like Jenkins.
This guide walks you through centralized log collection, explains the roles of Elasticsearch, Logstash, and Kibana, and provides step‑by‑step commands to install, configure, and verify a complete ELK logging pipeline for Linux servers.
This article examines common causes of Redis data loss, walks through a real‑world incident where 90,000 keys vanished, and provides concrete monitoring, configuration, and operational safeguards to detect and avoid such failures.
ZooKeeper's leader election mechanism creates temporary sequential nodes under a shared /ELECTION path, allowing services to elect a primary node, monitor predecessor nodes, and automatically re-elect a new leader when the current one fails, ensuring continuous high availability across distributed applications.
This article presents a comprehensive overview of hotel search ranking, covering problem definition, the distinction between ranking and probability estimation, handling position bias, detailed feature engineering, the AnyBoost linear boosting model, offline evaluation methods, and observed online performance improvements.
When a Linux, Windows, or Mac system fails to boot, you can use five lightweight, free Linux live distributions—Lubuntu, AntiX, Bodhi Linux, SliTaz, and TinyCore—to quickly boot the machine and copy important files to an external drive.
This guide introduces MySQL Utilities, demonstrates how to configure master‑slave replication in seconds using the mysqlreplicate command, explains required user creation, showcases additional tools like mysqldiskusage and mysqlindexcheck, and provides installation and download instructions.
This article provides a step‑by‑step beginner tutorial on GitHub, explaining what Git is, how to create repositories, clone them locally, make changes, commit and sync, roll back versions, and explore various non‑coding uses such as writing books, managing documents, and building personal sites.
Android app internationalization involves extracting hard‑coded strings into language‑specific strings.xml files, using Lint and regex to locate text, annotating resources, formatting placeholders, exporting for translation, updating the Resources configuration at runtime, handling UI refresh via onConfigurationChanged, recreate or activity restart, and adjusting layouts for length, dimensions, and caps to ensure a seamless multilingual experience.
This article explains how to achieve website scalability through physical separation, server clustering, various load‑balancing techniques, consistent‑hashing for distributed caches, and scaling strategies for relational and NoSQL databases, providing practical guidance for building resilient back‑end systems.
This article describes how Qunar replaced a low‑click hot‑words card with a personalized “You May Like” recommendation card, detailing data collection, rule‑based and collaborative‑filtering association methods, learning‑to‑rank models (subjective Bayes, RankBoost, LambdaMart), training‑sample strategies, online experiments, evaluation metrics, and future plans including LSTM‑based sequence modeling.
This article explains the basic principles of A/B testing, demonstrates a practical advertising experiment, describes effective experiment design, outlines Qunar's A/B testing platform architecture and workflow, and details statistical validation methods including Z‑test, minimum sample size calculation, and confidence interval estimation.
This article provides a comprehensive overview of Ceph's distributed storage architecture, its integration with OpenStack, internal data mapping mechanisms, advanced features like SSD caching and global object storage, and examines the key factors behind its widespread adoption in cloud environments.
Distributed locks prevent concurrent conflicts over shared resources in distributed systems, and this article explains ZooKeeper’s approach using ordered sequential nodes, illustrating the lock acquisition and release process with command-line examples and a complete Java implementation.
