To implement a Redis pool across different CentOS servers, you can use a combination of Redis Sentinel for high availability and Redis Cluster for sharding and data distribution. This setup allows you to have multiple Redis instances distributed across different servers, providing fault tolerance, data replication, and load balancing. Connecting to this cluster from PHP is very strightforward, just follow these simple steps.


Here's a high-level overview of the steps to implement a Redis pool with Redis Sentinel and Redis Cluster:


1. Set up Redis Sentinel:

Redis Sentinel monitors the health of Redis instances and manages failover in case a master node becomes unavailable.

a. Install Redis on all CentOS servers:
Ensure Redis is installed on each CentOS server that will be part of the pool. You can follow the installation steps provided in my previous response.

b. Configure Redis Sentinel on each server:
Modify the Redis configuration file (`redis.conf`) on each server to include Sentinel configuration. Set the Sentinel monitor to watch the Redis instances.

c. Start Redis Sentinel on each server:
Run Redis Sentinel on each server to monitor the Redis instances:

redis-sentinel /path/to/sentinel.conf

2. Set up Redis Cluster:

Redis Cluster allows you to distribute your data across multiple Redis instances for load balancing and scalability.

a. Configure Redis Cluster on each server:
Modify the Redis configuration file (`redis.conf`) on each server to include the Cluster configuration. Specify the cluster-enabled option and configure the cluster-node-timeout value. This an example Redis configuration file (redis.conf) that includes both Sentinel and Cluster configurations. Please note that this is a basic example, and you may need to adjust the configuration based on your specific needs and server setup.

# General configurations
port 6379
protected-mode yes
daemonize yes
pidfile /var/run/
logfile /var/log/redis/redis_6379.log

# Sentinel configurations
sentinel monitor mymaster 6379 2
sentinel down-after-milliseconds mymaster 30000
sentinel parallel-syncs mymaster 1
sentinel failover-timeout mymaster 180000

# Cluster configurations
cluster-enabled yes
cluster-config-file /etc/redis/nodes.conf
cluster-node-timeout 5000
cluster-announce-ip <IP_ADDRESS> # Replace with the IP address of this server
cluster-announce-port 6379
cluster-announce-bus-port 6380

# Memory and eviction policies (adjust based on your available RAM)
maxmemory 1gb
maxmemory-policy allkeys-lru

# Security (optional, enable if your Redis instance is exposed to the internet)
requirepass YourPasswordHere


b. Start Redis instances as part of the cluster:
Run Redis instances on each server, specifying the cluster configuration.

redis-server /path/to/redis.conf


c. Create the Redis Cluster:
On one of the servers, connect to one of the Redis instances and create the cluster:

redis-cli --cluster create node1_ip:port node2_ip:port node3_ip:port ...

Replace node1_ip:port, node2_ip:port, etc., with the IP and port of each Redis instance in the cluster.


3. Client Configuration:

Configure your PHP Redis clients to connect to the Redis pool using the Sentinel addresses for high availability and Redis Cluster addresses for data distribution.

$sentinelAddresses = [

$redis = new Redis();
$redis->connect($sentinelAddresses, $timeout);
$redis->setOption(Redis::OPT_SENTINEL, true);

// For Redis Cluster support
$redis->setOption(Redis::OPT_CLUSTER, Redis::FAILOVER_DISTRIBUTE);

With this setup, Redis Sentinel will monitor the Redis instances and promote a new master if a master node fails. Redis Cluster will handle data distribution and load balancing across the Redis instances. This combination provides you with a robust and scalable Redis pool across different CentOS servers.