This article investigates the high CPU usage and latency observed after expanding a large Redis cluster, analyzes the root cause in the CLUSTER SLOTS implementation and client MOVED handling, proposes an optimized slot‑traversal algorithm, and demonstrates significant performance improvements through benchmarking and profiling.
In large Redis clusters the original CLUSTER SLOTS implementation traversed every master and all 16,384 slots, causing ~52 % CPU usage and high MGET latency during migrations, but redesigning it to iterate the pre‑built slot array reduced complexity to O(total slots), cutting execution time from 2 ms to 0.17 ms and eliminating the CPU hotspot, a fix now merged into Redis 6.2.2.
This article explains the three Redis clustering modes, details how Redis Cluster uses 16384 hash slots calculated by CRC16, describes the rationale behind the slot count, and outlines the gossip‑based heartbeat communication and message format between master nodes.
Redis, an open‑source in‑memory data store, serves as a database, cache, and message broker, offering rich data types, persistence, replication, Sentinel, and clustering; this article walks through its evolution from simple caching to high‑availability, distributed architectures, and advanced client features.
This article introduces the main Redis scaling solutions—including simple partitioning, master‑slave replication, Sentinel high‑availability, and Redis Cluster—explaining their concepts, usage patterns, advantages, and drawbacks to help developers choose the appropriate architecture for high‑traffic environments.
This article details the design, deployment, configuration, operation, monitoring, and backup of a PostgreSQL high‑availability cluster built on Patroni, Etcd, and LVS at 360, covering hardware layout, software versions, installation steps, parameter tuning, fail‑over testing, and future outlook.
This article explains how to extend Redis beyond a single instance by covering partitioning, master‑slave replication, Sentinel automatic failover, and Redis Cluster, describing their usage methods, advantages, and drawbacks for high‑traffic, high‑availability scenarios.
This guide compiles nineteen common Kubernetes problems—from certificate errors and service exposure failures to pod initialization issues and Helm installation errors—providing concise root‑cause analyses and step‑by‑step command solutions to help you quickly troubleshoot and resolve cluster disruptions.
This guide walks through selecting a clustering strategy, installing Percona XtraDB Cluster (PXC) with Docker, configuring a five‑node cluster, adding HAProxy for load balancing, testing access, and handling node failures to achieve strong consistency and high availability for critical data.
This article explains how Redis Cluster uses hash slots for data partitioning, enables near‑linear scaling and fault‑tolerant failover through master‑slave replication, and requires client‑side routing support, while discussing the trade‑off between performance and consistency in distributed systems.
This guide explains how to set up a Percona XtraDB Cluster (PXC) using Docker containers, configure five-node replication with strong consistency, and implement HAProxy as a TCP load balancer to achieve high availability and balanced read/write traffic across the cluster.
This article provides a comprehensive overview of Redis interview questions, covering persistence mechanisms, cache avalanche and penetration, hot vs. cold data, differences from Memcached, single‑threaded performance, data structures, internal architecture, expiration policies, clustering options, distributed locks, and transaction handling.
MySQL Group Replication, introduced in 2016, delivers high‑availability, strong consistency, fault‑tolerant and scalable MySQL clusters through a Paxos‑based, plugin‑driven architecture that supports both single‑primary and multi‑primary modes, with detailed installation, configuration, deployment and testing guidance, while noting its limited current adoption due to ecosystem maturity.
This article reviews Redis's latest features and compares various deployment architectures—including single‑replica, dual‑replica, cluster, and read‑write‑separation modes—detailing their reliability, performance characteristics, suitable use cases, and provides a Java Jedis example for configuring a direct‑connect cluster.
This guide presents practical best‑practice configurations for Elasticsearch clusters in production, covering JVM heap sizing, CPU thread‑pool tuning, optimal shard counts, replica strategies, hot‑warm node architecture, node role settings, common troubleshooting tips, cache handling, refresh intervals, and essential monitoring APIs.
In a Redis cluster, bulk MGET calls suffered intermittent latency spikes because keys were distributed across many hash slots, forcing multiple network round‑trips; the issue can be mitigated by grouping keys with a common hash tag (though it reduces HA) or by issuing parallel slot‑wise MGETs with careful tuning, which preserves topology for larger batches.
This article outlines the new features of Redis 6.0 and 5.0, compares various deployment architectures such as master‑replica, single‑replica, cluster and read‑write split, presents typical usage scenarios, and provides a Java Jedis code sample for connecting to a Redis cluster.
This article reviews various cache system types, compares popular distributed caches such as Memcache, Tair, and Redis, explains Redis cluster high‑availability mechanisms, discusses sharding strategies, and outlines common cache problems and solutions, providing practical configuration examples for Java backend developers.
This tutorial walks you through creating four VirtualBox Linux VMs, configuring networking, disabling firewalls, installing Java and Perl, setting up password‑less SSH, and preparing a reusable cluster environment that can later host Redis, Kafka, or Storm clusters.
This article reviews Redis 6.0 and 5.0 new features, compares cluster, master‑replica, and read‑write separation architectures, explains proxy and direct connection modes, and provides Java code for custom connection pools, helping you select the optimal Redis deployment for your workload.
This article provides a detailed tutorial on Nacos, covering its advantages over Eureka, step‑by‑step setup for service registration and discovery, configuration management with dynamic refresh, shared configurations, persistence to MySQL, cluster deployment, and the trade‑offs between CP and AP modes in a cloud‑native microservices environment.
This article outlines the major new features of Redis 6.0 and 5.0, compares various deployment architectures—including master‑replica, cluster, and read‑write separation—explains proxy versus direct connection modes, and provides a Java Jedis connection‑pool code sample.
This article reviews Redis 6.0 and 5.0 new features, compares cluster, master‑replica (single and double replica), and read‑write‑separation architectures, explains their reliability and use‑case scenarios, and provides a Java/Jedis code sample for custom connection‑pool configuration.
This guide walks you through setting up a three‑node etcd cluster on CentOS 7 using static configuration and self‑signed TLS certificates, covering member addition and removal, data backup via snapshots, and full cluster restoration from those snapshots.
This article reviews Redis 6.0 and 5.0 new features, compares deployment architectures such as cluster, master-replica, and read-write split, and provides Java connection-pool code examples to help engineers select the appropriate Redis setup for performance, reliability, and scalability requirements.
Redis achieves its remarkable speed through a combination of in‑memory data storage, optimized data structures like SDS, ziplist, quicklist and skiplist, a single‑threaded command model, efficient I/O multiplexing, and sophisticated persistence, replication, Sentinel and Cluster mechanisms that together ensure high performance and reliability.
This article introduces Linux cluster fundamentals, explains key concepts such as scalability, high availability, load balancing, and error recovery, categorizes clusters into high‑availability, load‑balancing, and high‑performance types, and outlines common architectures, technologies, and implementation methods for building robust, fault‑tolerant systems.
Redis is an open‑source, in‑memory key‑value store that uses a compact memory model with SDS strings, offers RDB snapshots and AOF logging for persistence, supports master‑replica replication with full and partial sync, and provides high‑availability Sentinel and scalable sharding Cluster architectures.
This article recounts a real‑world MongoDB sharding incident on a core cluster with billions of records, detailing the root causes, step‑by‑step remediation using removeShard and movePrimary, and the lessons learned to prevent similar outages.
This article explains how Node.js handles processes, demonstrates creating child processes with fork, illustrates inter‑process communication (IPC) using send and message events, explores handle passing and shared ports, and shows how to build robust clusters with the built‑in cluster module.
A latency‑sensitive MongoDB cluster experienced severe jitter and connection exhaustion when multiple background indexes were added sequentially, revealing how index builds overload replica nodes, trigger alerts, and can be mitigated with proper index‑addition strategies and the noIndexBuildRetry option.
This comprehensive tutorial walks you through preparing the environment, configuring the OS, setting up ASM disk groups, installing Oracle Grid Infrastructure, creating ASM disks, and building a database on a CentOS 7 cluster, complete with detailed screenshots for each step.
This article explains Redis Cluster's decentralized sharding design, the role of master‑slave replication for high availability, and how strong consistency is achieved using consensus protocols such as Raft, highlighting key concepts like global log indexes and commit pointers.
This article examines common performance pitfalls in Elasticsearch—including slow queries, cluster architecture bottlenecks, and business‑scenario challenges—and provides practical guidance such as caching key fields, data pre‑heating, hot‑cold separation, avoiding joins, and using tribe nodes to improve accuracy and response time.
This article explains process and thread fundamentals, describes Node.js's single‑threaded nature, and provides detailed guidance on using the child_process module (spawn, fork, exec, execFile) and the cluster module to create, manage, and communicate between multiple Node.js processes for scalable, high‑concurrency applications.
This article explains why Redis can lose data during asynchronous master‑slave replication failures or split‑brain partitions, and shows how configuring min‑slaves‑to‑write and min‑slaves‑max‑lag, along with client‑side fallback strategies, can greatly reduce the risk of loss.
This article provides a comprehensive analysis of Redis Cluster, covering node and slot assignment, command execution, resharding, redirection, failover, gossip messaging, and communication overhead, while explaining why clustering is needed, how it works, and how to deploy and manage it effectively.
This guide explains why etcd backup is critical for Kubernetes disaster recovery, walks through snapshot creation, distribution, scheduled cron jobs, and provides a step‑by‑step procedure to restore the cluster on all nodes, ensuring services resume correctly.
This article provides a comprehensive analysis of Redis Cluster, covering node and slot assignment, command execution, resharding, redirection, fault‑tolerance, gossip communication, scaling strategies, configuration limits, and practical code examples for building and operating a high‑availability sharded Redis deployment.
The article explains how asynchronous replication and split‑brain situations can cause data loss in Redis clusters, and describes configuration parameters and client‑side techniques to minimize such loss while maintaining high availability.
This article introduces Redis, explains why it is popular, describes the architecture of a Redis Cluster, and provides a complete step‑by‑step tutorial for deploying, initializing, validating, and testing a Redis Cluster on Kubernetes with sample code and a hit‑counter application.
This comprehensive guide explains MongoDB cluster components, common use cases, monitoring commands, basic operational tasks, data migration procedures, troubleshooting of production issues, and optimization recommendations to achieve high performance and scalability.
This guide explains the fundamentals of etcd, its Raft‑based architecture, cluster planning, secure certificate generation, installation steps, service configuration, and verification commands to deploy a reliable, SSL‑protected etcd cluster for service discovery and configuration management.
This article provides a thorough overview of Redis, covering its core data structures, common commands, persistence options, memory management, pipelining, transactions, performance optimization, replication, clustering, and Java client choices for developers and architects.
This article introduces Apache ZooKeeper as a high‑availability coordination service, explains its three deployment modes, core roles, hierarchical data model and node types, outlines common use cases such as configuration management, naming service, distributed locks and queues, and provides a step‑by‑step Docker‑Compose setup with example commands and configuration files.
This article demonstrates how to reproduce the session loss problem in a load‑balanced Spring Boot application, explains its cause, and provides a step‑by‑step solution using Redis for shared session storage, including code, Nginx configuration, and deployment instructions.
This tutorial walks through building a Redis Cluster on Redis 6.0+, covering node startup, handshaking, slot assignment, master‑slave replication, command routing, failover handling, and practical scaling operations such as adding, rebalancing, and removing nodes using redis‑cli commands.
This article provides a step‑by‑step tutorial on building a Redis Cluster on a single server, covering node configuration, cluster handshaking, slot assignment, master‑slave replication, command routing, failover handling, and practical scaling operations such as adding and removing nodes using redis‑cli.
Redis instances provide 16 default logical databases that act as namespaces rather than separate data stores; this article explains their origin, how to configure the number of databases, proper usage of SELECT and FLUSHALL commands, and why multiple databases are unsupported in Redis Cluster mode.
This tutorial walks through building a Redis 6+ cluster on a single server, covering node startup, cluster handshake, slot assignment, master‑slave replication, command routing, failover handling, and practical scaling operations such as adding and removing nodes.
This guide explains how to delete inconsistent Kubernetes rc, deployment, and service objects, reset etcd data, address apiserver start failures caused by missing ServiceAccount certificates, disable SELinux for fluentd logs, generate ServiceAccount keys, recover from etcd startup errors, configure host trust, change hostnames, enable VirtualBox copy‑paste, force‑delete pods and namespaces, and avoid resource‑request‑only containers causing contention.
This tutorial walks through setting up a Redis Cluster on a single server with six nodes, covering node startup, handshake, slot assignment, master‑slave replication, command routing, fault‑tolerance, and practical scaling operations such as adding, rebalancing, and removing nodes.
This tutorial walks through setting up a Redis Cluster on a single server with six nodes, covering node startup, handshake, slot assignment, master‑slave replication, command routing, failover handling, and practical scaling operations such as adding, rebalancing, and removing nodes.
This article introduces Elasticsearch’s core concepts—including clusters, node roles, documents, mappings, and shards—and walks through the complete indexing workflow from client request to replica synchronization, highlighting key settings, routing calculations, and the role of refresh and flush operations.
This article explains why Redis creates 16 logical databases by default, how to configure their number, the correct way to treat these databases as namespaces rather than separate stores, and why multiple databases are not supported in Redis Cluster mode.
This article provides a step‑by‑step guide for manually building a six‑node Redis cluster on macOS, detailing environment setup, configuration changes, node startup, slot allocation, and converting master nodes to slaves, with screenshots and command examples.
This article explains the mechanisms of Redis master‑slave data synchronization—including full and partial resynchronization—details the internal workings of Redis clustering, slot assignment, automatic node detection, and failover recovery, and provides practical insights for building reliable Redis deployments.
Elasticsearch combines Lucene’s inverted index with a distributed cluster of master‑eligible, data, and coordinating nodes, using Zen discovery for node election and split‑brain prevention, while indexing writes to primary shards, replicating to replicas, storing immutable segments that are periodically merged for efficient search.
This article provides a detailed collection of basic Elasticsearch interview questions and answers, covering core concepts such as cluster and node architecture, indexing, mapping, search APIs, analyzers, tokenizers, aggregation, security, and operational tools, along with practical code snippets for common tasks.
This guide walks through installing etcd, launching a static three‑node pseudo‑cluster on a single host, explains key command‑line flags, and shows how to deploy, configure, and scale the etcd cluster in Kubernetes using a corrected StatefulSet manifest.
This guide explains how to set up a simple two‑node Elasticsearch cluster in a cloud environment, covering prerequisite checks, installation, configuration of master and slave nodes, certificate handling, password setup, and verification of the cluster’s health.
This guide walks you through constructing a 28‑core Raspberry Pi 3B cluster named Kraken, upgrading it with USB gigabit adapters, configuring Docker Swarm and Kubernetes, and measuring performance improvements for self‑hosting a WordPress site.
This guide consolidates practical Elasticsearch tuning techniques—from configuration file settings and system‑level adjustments to usage‑level optimizations—covering memory locking, discovery, fault detection, queue sizing, JVM heap, file descriptors, translog handling, bulk indexing, shard management, and best practices to achieve a stable, high‑performance cluster.
This article introduces HBase’s column‑oriented architecture, explains the roles of Master, RegionServer, and Zookeeper, and provides detailed environment preparation and installation commands for setting up an HBase cluster on Hadoop.
This article walks through Redis’s role as an in‑memory data store, explains how simple HTTP caching evolves into server‑side memory caching, and details the progression to high‑availability and distributed architectures with persistence, Sentinel, replication, clustering, and advanced features like transactions, Lua scripting, pipelining, and distributed locks.
This article explains why Redis clusters are needed, how CLUSTER MEET builds the network, slot assignment, scaling procedures, client redirection mechanisms, batch operations, fault detection, recovery processes, and common operational pitfalls, providing practical guidance for building and maintaining a robust Redis Cluster deployment.
This article provides a comprehensive overview of RabbitMQ, covering its origins, core components, message routing patterns, persistence mechanisms, delivery modes, RPC support, clustering design, mirrored‑queue architecture, and flow‑control strategies for building reliable backend systems.
This article explains Eureka's role as a Spring Cloud service registry, detailing its server and client components, registration and renewal processes, self‑preservation mechanism, clustering principles, and the complete workflow that enables reliable microservice discovery and high availability.
This article explains how Suning's big‑data center leverages ClickHouse’s columnar OLAP engine and a full‑chain monitoring platform to achieve real‑time query tracing, slow‑query analysis, cluster health checks, and resource‑level alerts across diverse business scenarios.
This guide walks through the complete process of setting up a fault‑tolerant RocketMQ cluster on two Linux servers, covering environment preparation, Java installation, NameServer and Broker deployment, configuration of master‑slave modes, startup commands, troubleshooting, port opening, verification, and optional console installation.
This article explains the architecture and practical techniques for achieving high availability in Kubernetes clusters, covering control‑plane and worker‑node design, network service handling, connection reuse, node eviction, storage considerations, and application‑level strategies to ensure continuous service during node failures.
This tutorial walks through building a three‑node ClickHouse cluster, configuring host mappings and XML files, setting up ZooKeeper for internal replication, creating local and distributed tables, testing data insertion and queries, and demonstrating how to achieve high availability with replicated tables.
This article provides a detailed, step‑by‑step tutorial on building a six‑node Redis cluster on a single Linux machine, covering directory setup, configuration files, Ruby‑based cluster tools, instance startup, cluster creation, verification, online scaling, slot rebalancing, and using Redis for session sharing.
This article provides a comprehensive guide to Redis deployment, covering standalone, master‑slave replication, Sentinel high‑availability, and cluster sharding modes, detailing their principles, advantages, drawbacks, and step‑by‑step configuration examples with Maven dependencies and Redis configuration files.
The article explains how to achieve Kubernetes high availability by designing a three‑node control‑plane with stacked etcd, using pod anti‑affinity, tuning node‑monitor timers, handling stale endpoints, configuring TCP keep‑alive, managing node taints and eviction, and choosing RWX storage or appropriate StatefulSet strategies to minimize service disruption after node failures.
This guide walks you through setting up a fault‑tolerant RocketMQ cluster on two CentOS 7 machines, covering deployment options, environment preparation, Java installation, NameServer and Broker configuration, startup procedures, troubleshooting, and optional console installation.
This article explains Redis as an open‑source in‑memory data store used for caching, database, and messaging, walks through its evolution from simple HTTP caching to server‑side Redis, and details core features such as persistence, high availability, clustering, data types, transactions, Lua scripting, pipelining, and distributed locking.
This article explains what a PodSecurityPolicy is, details its configurable fields such as RunAsUser, SELinux, supplemental groups, FSGroup, and volume restrictions, and provides step‑by‑step commands to create, list, edit, delete, and enable PSPs in a Kubernetes cluster.
During a high‑traffic load test of an e‑commerce product detail page, excessive Redis cluster and PSETEX commands caused CPU spikes, and the investigation revealed that using millisecond‑level expiration in Spring Data Redis triggers frequent cluster node lookups, which can be resolved by switching to second‑level expirations.
This article explains Redis Cluster’s automatic sharding, built‑in high availability, the role of the cluster bus ports, the limitations of traditional hash algorithms, and how consistent hashing with virtual nodes and the 16384‑slot hash slot mechanism enable efficient data distribution and low‑cost node scaling.
This tutorial walks you through compiling Redis from source, configuring six cluster nodes on ports 7000‑7005, adjusting system memory settings, creating startup scripts, launching the services, forming the cluster, verifying its status, and testing basic read/write operations, all with detailed command examples.
This guide walks through the complete offline installation of OpenShift Container Platform, covering preparation of offline resources, server planning, firewall and DNS configuration, load‑balancer setup with Envoy, creation of ignition files, bootstrap, master and worker node provisioning, CSR approval, operator validation, and final cluster verification.
This article provides a comprehensive, step‑by‑step tutorial on creating a Redis Cluster using Docker, covering the preparation of a base Redis image, building node images, configuring cluster settings, assigning hash slots, adding replica nodes for high availability, testing failover, and solving network connectivity issues for production deployments.
This article explains how to extend Redis beyond single‑node limits by using partitioning, master‑slave replication, Sentinel for automatic failover, and Redis Cluster with hash slots, detailing their usage, advantages, drawbacks, and configuration examples for building high‑availability and scalable in‑memory data stores.
This tutorial walks through compiling the php‑redis extension, installing Laravel, configuring Redis as a cache and database driver, setting up a Redis cluster, and provides sample PHP code for read/write operations, offering a comprehensive guide for backend developers.
This step‑by‑step guide shows how to create a highly available Nginx load‑balancing cluster with Keepalived in both master‑slave and dual‑master configurations, covering server preparation, Nginx and Keepalived setup, VIP handling, testing, and a watchdog script to ensure service continuity.
This article provides a comprehensive tutorial on Redis Cluster, covering its architecture, data partitioning and redundancy, step‑by‑step instructions for downloading, compiling, and installing Redis on CentOS, as well as detailed procedures for manually or automatically creating a six‑node cluster with master‑slave replication and slot allocation.
This comprehensive guide explains what Redis is, its advantages and drawbacks, why it excels as a high‑performance cache, the supported data structures, persistence mechanisms, memory eviction policies, threading model, transaction handling, clustering and sharding options, distributed locking, common cache pitfalls, and useful tooling for Java developers.
This article explains what Redis Cluster is, how it partitions data and provides redundancy, and walks through installing Redis on CentOS, configuring multiple nodes, and creating a functional cluster using both manual commands and the built‑in cluster management tool.
This article walks through a real‑world ZooKeeper incident where a five‑node cluster showed two leaders, explains the election rules, analyzes log and configuration mismatches, assesses business impact, and provides a step‑by‑step recovery plan to restore normal service without data loss.
This article provides a comprehensive guide to Redis, covering atomic transactions, command pipelining, publish/subscribe messaging, data replication, high‑availability with Sentinel, and the distributed architecture of Redis Cluster, complete with code examples and configuration steps.
During the COVID‑19 surge, Tencent Cloud Redis scaled losslessly by using a proprietary slot‑specific RDB sync method that avoids downtime, handles large keys, Lua scripts, and multi‑key commands, outperforming open‑source and DTS approaches while minimizing resource duplication and maintaining 24/7 service.
The article explains how the shift from relying on ever‑faster hardware to adopting distributed architectures and cloud‑computing concepts reshapes system design, detailing core components, differences between clusters and distributed systems, and practical examples for developers seeking deeper technical insight.
This article provides a clear, visual guide to Kubernetes fundamentals, covering its six-layer abstraction, the roles of Deployments, ReplicaSets, Pods, Nodes, and Docker containers, followed by an overview of seven key API objects that drive container orchestration.
This article explains how Kubernetes 1.2 enables a single cluster to operate across multiple zones within the same cloud provider, detailing automatic zone labeling, pod and volume scheduling behavior, and the key limitations and considerations for multi‑zone deployments.
This article explains Node.js's internal concurrency model, covering the distinction between processes and threads, debunking the single‑thread myth, and detailing how the event loop, child processes, cluster mode, and worker_threads enable high‑performance, multi‑core execution.
This article provides a comprehensive overview of ElasticSearch, covering its distributed architecture, fundamental components such as nodes, shards, and indices, as well as practical guidance on index design, mapping, bulk operations, query processing, scroll searches, alias management, and performance tuning tips.
Redis creates 16 logical databases by default, a design inherited from its early architecture; this article explains the origin of that number, how to modify it via configuration, the proper way to view these databases as namespaces, and the limitations when using Redis in cluster mode.
This comprehensive guide explores Redis caching fundamentals, data structures, key‑search techniques, distributed lock implementation, asynchronous queues, persistence options (RDB, AOF, hybrid), pipeline usage, replication, Sentinel monitoring, and cluster sharding with consistent hashing to help developers build high‑performance, reliable systems.
This article provides a comprehensive overview of Redis, explaining its core data structures, caching use cases, persistence mechanisms, high‑availability features like Sentinel and replication, clustering for horizontal scaling, and client‑side capabilities such as transactions, Lua scripting, pipelining, and distributed locks.
