Cluster Mode

cachly Cluster Mode uses Valkey Cluster under the hood to horizontally shard your data across multiple nodes – with automatic failover and linear throughput scaling.

Architecture

┌──────────────┐    ┌──────────────┐    ┌──────────────┐
│  Shard 0     │    │  Shard 1     │    │  Shard 2     │
│  slots 0-5460│    │  5461-10922  │    │  10923-16383 │
│  Primary + R │    │  Primary + R │    │  Primary + R │
└──────────────┘    └──────────────┘    └──────────────┘
        ↕                   ↕                   ↕
   ┌────────────────────────────────────────────────┐
   │           cachly Smart Router (Proxy)          │
   └────────────────────────────────────────────────┘
        ↕
   Your Application

Each shard holds a subset of the 16384 hash slots. cachly's smart proxy routes commands to the correct shard automatically – your application connects to a single endpoint.

Features

📈

Linear Scaling

Add shards to increase throughput and memory linearly. No single-node bottleneck.

🔄

Automatic Failover

If a primary fails, its replica is promoted within seconds. Zero manual intervention.

🎯

Smart Routing

cachly's proxy handles MOVED/ASK redirections transparently. Your app sees one endpoint.

🔑

Hash Tags

Use {tag} notation to colocate related keys on the same shard for multi-key operations.

📊

Per-Shard Metrics

Memory, ops/sec, and latency metrics broken down by shard in Grafana.

🌍

Multi-Region Ready

Deploy replicas in different regions for read-local latency.

Enabling Cluster Mode

Cluster Mode is available on the Pro and Enterprise tiers. Enable it when creating an instance:

POST /api/v1/instances
{
  "name": "prod-cluster",
  "engine": "valkey",
  "tier": "pro",
  "cluster": {
    "enabled": true,
    "shards": 3,
    "replicas_per_shard": 1
  }
}

Terraform Example

resource "cachly_instance" "cluster" {
  name   = "prod-cluster"
  engine = "valkey"
  tier   = "pro"

  cluster {
    enabled            = true
    shards             = 3
    replicas_per_shard = 1
  }
}

See the Terraform docs for the full provider reference.

Hash Tags for Key Colocation

By default, keys are distributed across shards by hashing the full key. Use {tag} notation to ensure related keys land on the same shard:

SET {user:42}:profile "..."
SET {user:42}:sessions "..."
SET {user:42}:prefs "..."
# All three keys colocate on the same shard → MULTI/EXEC works

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