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Redis

Monitor Redis server health and performance, including CPU, memory, replication, command statistics, connections, and keyspace activity.

Guides

Guides overview 1 page

Redis Operations Guides

Practical guides for running, troubleshooting, and monitoring Redis in production.

Redis Operations Guides 31 pages

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MISCONF Redis is configured to save RDB snapshots - what it means and how to fix it

Fix the Redis MISCONF error that blocks writes when a background RDB save fails. Diagnose root causes, recover safely, and understand the stop-writes-on-bgsave-error guard.

Redis aof_last_write_status:err: AOF write failures and recovery

Diagnose and recover when Redis AOF writes fail, including disk full, I/O errors, and the path from aof_last_write_status:err back to ok.

Redis big keys: finding the giant key that blocks the event loop

Diagnose and fix Redis latency caused by oversized keys and O(N) commands blocking the single-threaded event loop.

Redis BUSY Redis is busy running a script: blocking Lua and how to recover

Troubleshoot the Redis BUSY error from long-running Lua scripts. Learn how SCRIPT KILL, SHUTDOWN NOSAVE, and lua-time-limit work, and how to prevent event-loop blocking.

Redis Can't save in background: fork: Cannot allocate memory - diagnosis and fix

Why Redis background saves fail with fork: Cannot allocate memory, how to diagnose vm.overcommit_memory and COW pressure, and how to fix it without restarting Redis.

Redis client output buffer overflow: slow consumers and client-output-buffer-limit

Diagnose and fix Redis client output buffer overflow from slow consumers, including omem analysis, client-output-buffer-limit tuning, and MONITOR detection.

Redis cluster bus port blocked: the port+10000 firewall gotcha

Diagnose and fix Redis Cluster failures caused by a blocked gossip bus port (port+10000), where symptoms mimic network partition but the fix is a firewall rule.

Redis cluster_slots_pfail > 0: impending node failure in a cluster

Investigate Redis Cluster PFAIL before it escalates to FAIL. Learn the gossip mechanism, quorum rules, zombie states, and how to distinguish transient pauses from real node failure.

Redis CLUSTERDOWN / cluster_state:fail: slot coverage and recovery

Diagnose and recover when Redis Cluster reports cluster_state:fail or clients see CLUSTERDOWN due to missing hash slot coverage.

Redis connected_clients climbing: connection leak detection

Diagnose and fix a sustained climb in Redis connected_clients when traffic is flat, including CLIENT LIST analysis, timeout configuration, and connection churn detection.

Redis connection exhaustion: leaks, pools, and the retry storm

Diagnose and fix Redis connection exhaustion, from pool misconfiguration and client leaks to retry storms that amplify the outage.

Redis CPU saturation: hitting the single-core throughput ceiling

Diagnose Redis main-thread CPU saturation. Learn why single-threaded command execution creates a linear latency ramp, which metrics expose it, and how to relieve the bottleneck.

Redis event loop blocked: when one slow command freezes everything

Diagnose and fix Redis event loop blocking caused by slow commands, Lua scripts, and large key operations.

Redis eviction policy tuning: allkeys-lru vs volatile-ttl vs noeviction

How Redis maxmemory eviction policies work, when each policy is the right choice, and how to detect when the wrong policy is causing silent failures or OOM write rejections.

Redis exposed without authentication: the CONFIG SET dir crontab attack

Detect, audit, and lock down unauthenticated Redis instances against the classic CONFIG SET dir crontab attack and modern follow-on exploits.

Redis FLUSHALL ran in production: detection, prevention, and recovery

Detect, recover from, and prevent accidental or malicious FLUSHALL and FLUSHDB execution in production Redis deployments.

Redis fork/COW memory storm: why persistence doubles RSS and OOM-kills the box

Why Redis background saves trigger copy-on-write memory spikes that double RSS and OOM-kill containers, and how to diagnose, fix, and prevent them.

Redis KEYS command blocking production: why to replace it with SCAN

Diagnose and fix Redis production outages caused by the KEYS command blocking the single-threaded event loop, and replace it with SCAN.

Redis latest_fork_usec too high: THP, NUMA, and fork latency

Diagnose and fix elevated Redis fork latency caused by Transparent Huge Pages, NUMA misconfiguration, and memory overcommit issues.

Redis MASTERDOWN / master_link_status:down: replication link broken

Diagnose and fix a Redis replica when master_link_status flips to down, the replication link breaks, and stale reads are served.

Redis max number of clients reached: maxclients and rejected_connections

Diagnose and resolve Redis maxclients exhaustion, rejected_connections spikes, and connection pool leaks with CLIENT LIST, CLIENT KILL, and ulimit tuning.

Redis maxmemory not set: why every production instance needs a memory limit

Running Redis without maxmemory is the most common production misconfiguration. Learn how to size it, pair it with an eviction policy, and avoid OOM kills.

Redis memory pressure spiral: eviction thrashing and how to break it

Diagnose and break the Redis memory pressure spiral where eviction, cache misses, and re-population writes feedback into each other.

Redis monitoring checklist: the signals every production instance needs

A production monitoring checklist for Redis organized by maturity level, from survival signals to expert-grade metrics that prevent silent degradation.

Redis OOM command not allowed when used memory > 'maxmemory' - causes and fixes

Troubleshoot Redis write rejections caused by maxmemory exhaustion under noeviction or volatile policies, diagnose silent failures, and fix the root cause without guessing.

Redis OOM-killed by the kernel: RSS, overcommit, and recovery

Why Redis dies to the kernel OOM killer even when used_memory looks healthy, how to diagnose RSS bloat from fragmentation and COW, and how to recover.

Redis rdb_last_bgsave_status:err: diagnosing failed background saves

Diagnose why Redis background saves fail and recover from `rdb_last_bgsave_status:err` without guessing.

Redis READONLY You can't write against a read only replica - causes and fixes

Diagnose and fix the Redis READONLY error when applications write to a replica, including routing bugs, stale topology after failover, and runtime misconfigurations.

Redis replication backlog overflow: full-resync storms and the 1MB default

Diagnose and break replication backlog overflow loops in Redis, where a 1MB default triggers full resync storms that fork the primary and cascade latency to every replica.

Redis replication lag: detection, diagnosis, and fixes

Troubleshoot Redis replication lag by measuring byte-level offsets, identifying resource bottlenecks on replicas, and preventing full resync cascades caused by undersized backlogs.

Redis sync_full incrementing: diagnosing full resync events

Diagnose why Redis sync_full counters are climbing, identify replication backlog exhaustion, and stop full resync storms before they overwhelm the primary.

Academy

Redis Sentinel Failover & Split-Brain Recovery Guide

Learn to decode Redis Sentinel logs to identify network partitions and prevent inconsistent cluster states during failover events

Redis Monitoring

Learn everything about monitoring & troubleshooting Redis, what metrics are important to monitor and why, and how to monitor Redis with Netdata.

Redis Queue Monitoring

Learn everything about monitoring & troubleshooting Redis Queue, what metrics are important to monitor and why, and how to monitor Redis Queue with Netdata.

Case Studies

Motohunt Case Study: Automotive Industry Monitoring

Achieving Optimal Performance and Cost Efficiency with Real-Time Insights

Overcoming Monitoring Challenges in Shared VM Environments

Elevating Operational Efficiency with Netdata

Monitoring Industrial Equipment Manufacturing with Netdata

Harnessing Real-Time Insights for Scalable and Reliable Production

Easy Doc: Revolutionizing IT Operations with Netdata

Harnessing Real-Time Insights for Enhanced Container and Cluster Health

Codyas: Global Server Management with Netdata

Achieving Efficiency and Security Across Diverse Infrastructures

Resources

Best Redis Monitoring Tools: 10 Options Ranked for 2026

The 10 best Redis monitoring tools ranked for 2026, compared on metric depth, collection resolution, alerting, setup effort, and pricing for real fleets.

Blog

Database Performance Monitoring: 14+ DBs Supported

Slow queries, running operations, deadlocks, and errors for PostgreSQL, MySQL, MongoDB, SQL Server, Oracle, and more.

Release 1.37: Infinite Scalability & Database Tiering

Continuing to Innovate and Improve with New Release Features

7 types of Redis latency and how to fix it

A Game-Changer for DevOps and Developers