redis-replication
Master Redis replication - master-replica setup, Sentinel for HA, failover handling, and read scaling patterns
When & Why to Use This Skill
This Claude skill provides a comprehensive technical runbook for mastering Redis replication and High Availability (HA). It covers master-replica configurations, automated failover using Redis Sentinel, and strategies for read scaling. Designed for DevOps engineers and Database Administrators, it includes production-ready configurations, monitoring metrics, and troubleshooting guides to ensure database reliability, minimize downtime, and optimize performance in distributed environments.
Use Cases
- Setting up master-replica architectures to scale read operations and improve data redundancy across multiple nodes.
- Implementing Redis Sentinel for automated health monitoring and failover handling to ensure 24/7 service availability.
- Diagnosing and resolving critical replication issues such as synchronization failures, authentication errors, and replication lag.
- Configuring split-brain prevention and quorum settings to maintain data consistency during network partitions.
- Monitoring database health using key metrics like connected replicas and master link status for proactive maintenance.
| name | redis-replication |
|---|---|
| description | Master Redis replication - master-replica setup, Sentinel for HA, failover handling, and read scaling patterns |
| sasmp_version | "1.3.0" |
| bonded_agent | 06-redis-clustering |
| bond_type | PRIMARY_BOND |
| version | "2.1.0" |
| last_updated | "2025-01" |
| type | integer |
| required | false |
| enum | [basic_replication, sentinel] |
| default | 2 |
| max_retries | 5 |
| backoff_strategy | exponential |
| backoff_base_ms | 1000 |
Redis Replication Skill
Master-Replica Setup
Replica Configuration
replicaof master_ip 6379
masterauth your_password
replica-read-only yes
replica-serve-stale-data yes
Commands
REPLICAOF master_ip 6379 # Set master
REPLICAOF NO ONE # Promote to master
INFO replication # Check status
Sentinel (Auto-Failover)
Architecture
Sentinel 1 Sentinel 2 Sentinel 3
↓ ↓ ↓
└──────── Monitor ───────────┘
↓
Master ←──→ Replica 1 ←──→ Replica 2
Configuration
# sentinel.conf
port 26379
sentinel monitor mymaster 192.168.1.10 6379 2
sentinel auth-pass mymaster password
sentinel down-after-milliseconds mymaster 5000
sentinel failover-timeout mymaster 60000
sentinel parallel-syncs mymaster 1
Commands
# On Sentinel port
SENTINEL masters
SENTINEL get-master-addr-by-name mymaster
SENTINEL failover mymaster
SENTINEL replicas mymaster
Monitoring
INFO replication
# role:master|slave
# connected_slaves:2
# slave0:ip=...,port=...,state=online,offset=...,lag=0
Assets
sentinel.conf- Sentinel configurationdocker-compose-ha.yml- HA Docker setup
References
REPLICATION_GUIDE.md- Setup guide
Troubleshooting
Replica Not Syncing
INFO replication # Check master_link_status
Fix: Check network, password, and firewall
Split-Brain Prevention
min-replicas-to-write 1
min-replicas-max-lag 10
Failover Not Triggering
Check: Quorum (need majority of Sentinels)
Error Codes
| Code | Name | Recovery |
|---|---|---|
| R001 | MASTERDOWN | Check master or failover |
| R002 | SYNC_FAILED | Check network/auth |
| R003 | QUORUM_LOST | Restore Sentinel majority |