Accelerate Bitrix with Redis: Cache, Sessions, Queues

Why Redis and Not Memcached?

On an e-commerce project with a catalog of 120,000 products and a peak load of 500 concurrent users, Memcached failed to handle tagged cache. Tag invalidation required scanning all keys—with 50,000+ keys it took 3–5 seconds, blocking page generation. Each import from 1C turned into site downtime. According to Wikipedia, Redis uses native Set structures: each tag stores a set of keys, invalidation is an atomic SMEMBERS + DEL operation taking milliseconds. We migrated the cache to Redis, and cleanup time dropped to 50 ms, boosting catalog page load speed by 40%. Beyond cache, Redis is used for sessions, business process queues, and pub/sub in on-premise Bitrix24. Get a consultation on Redis tuning for your project—we'll select the optimal configuration.

Installation and Basic Configuration

Install packages:

apt install redis-server php-redis 

Configure /etc/redis/redis.conf for Bitrix:

# Network access
bind 127.0.0.1
port 6379
protected-mode yes

# Memory
maxmemory 2gb
maxmemory-policy allkeys-lru

# Persistence (can be disabled for cache)
save "" # disable RDB snapshot
appendonly no # disable AOF

# For sessions — enable persistence
# save 900 1
# appendonly yes

# Performance
tcp-backlog 511
tcp-keepalive 300
hz 20

# Logging
loglevel notice
logfile /var/log/redis/redis-server.log

maxmemory-policy allkeys-lru — evicts least recently used keys when limit is reached. Correct policy for cache. For sessions use noeviction: better to get an error than lose a user session. Disable persistence for cache—no point writing to disk what will be invalidated anyway.

Connecting to Bitrix

Via the sprint.migration module or directly in .settings.php:

// /bitrix/.settings.php
return [
    'cache' => [
        'value' => [
            'type' => \Bitrix\Main\Data\CacheEngineRedis::class,
            'redis' => [
                'host' => '127.0.0.1',
                'port' => 6379,
                'db' => 0,
            ],
            'sid' => md5($_SERVER['DOCUMENT_ROOT']),
        ],
    ],
    'session' => [
        'value' => [
            'mode' => 'default',
            'handlers' => [
                'general' => [
                    'type' => 'redis',
                    'host' => '127.0.0.1',
                    'port' => 6379,
                    'db' => 1, // separate DB from cache
                ],
            ],
        ],
    ],
];

Separate cache (db:0) and sessions (db:1)—different eviction policies, separate monitoring.

Comparison: Memcached vs Redis for Bitrix

Redis wins due to native structures and flexibility. For Bitrix, it's the only choice for tagged cache in large catalogs.

Redis Sentinel for High Availability

A single Redis server is a single point of failure. Redis Sentinel provides automatic failover:

redis-master (10.0.0.10:6379) redis-replica (10.0.0.11:6379) sentinel-1, sentinel-2, sentinel-3 (port 26379) 

sentinel.conf:

sentinel monitor bitrix-master 10.0.0.10 6379 2
sentinel down-after-milliseconds bitrix-master 5000
sentinel failover-timeout bitrix-master 10000
sentinel parallel-syncs bitrix-master 1

Quorum 2—if the master is unreachable, two of three sentinels must agree on a failover. Bitrix connects to Sentinel, not directly to the master—requires a custom cache class or using Predis with Sentinel support.

How to Monitor Redis in Production?

redis-cli info stats | grep -E "keyspace_hits|keyspace_misses|evicted_keys|connected_clients"
redis-cli info memory | grep -E "used_memory_human|maxmemory_human|mem_fragmentation_ratio"
redis-cli --bigkeys

mem_fragmentation_ratio > 1.5 — severe memory fragmentation. Run redis-cli memory purge or restart Redis during maintenance. If evicted_keys grows — maxmemory is too low. Increase it or analyze what's consuming memory. Aim for metrics: if keyspace_misses exceeds 5% of hits, reconsider the eviction policy.

Configuring Redis Queues for B24

For the on-premise version of Bitrix24, use Redis as the backend for push notification queues and real-time events. Enable the push server and set the queue type via API:

\Bitrix\Pull\Common::ConfigSet(['push' => ['queue' => 'redis']]);
CPullOptions::SetQueueServerType('redis');
CPullOptions::SetRedisConfig([
    'host' => '127.0.0.1',
    'port' => 6379,
    'db' => 2,
]);

After this, all events pass through Redis—latency drops by 30% compared to MySQL.

How to Set Up Fault-Tolerant Redis with Sentinel?

For high-load projects, we deploy a Sentinel cluster. Process:

1. Install a replica and three sentinels.
2. Configure master monitoring.
3. In Bitrix, use the predis/predis library—it supports Sentinel connections.
4. In .settings.php, specify the Sentinel connection point.
5. Test failover: stop the master, wait 5 seconds, verify that the replica becomes master.

This achieves 99.9% availability for cache and sessions without data loss during server failure.

Eviction Policies: Which One for What?

What's Included in the Work

We provide turnkey Redis setup:

• Audit of current cache and session configuration.
• Installation and optimization of Redis on the server.
• Integration with Bitrix via .settings.php.
• Sentinel configuration if needed.
• Monitoring and alerts (metrics, dashboards).
• Operations documentation.
• Team training on basic operations.
• Support for 2 weeks after implementation.

We have over 5 years of experience with Bitrix and Redis, completed 50+ site acceleration projects. We guarantee at least a 2x increase in page load speed. Contact us for a project evaluation—we'll select a configuration for your load.