Question: How can you set up a Redis cluster without replicas?

Answer

Setting up a Redis cluster without replicas involves creating several standalone Redis instances, running each on a different port, and then using the redis-cli tool to create the cluster.

Here is a brief step-by-step guide:

  1. Ensure that Redis is installed on your system.

  2. Run multiple standalone Redis instances on different ports. You would typically do this manually by executing a command for each instance, specifying a different port number:

    redis-server --port 6379 redis-server --port 6380 # Continue in this manner for as many instances as needed
  3. Once all the desired Redis instances are running, use the redis-cli tool to create the cluster. The --cluster create command takes as arguments all the IPs and ports of the nodes to be included in the cluster. Suppose we have three Redis instances running at ports 6379, 6380, and 6381 on localhost, we would execute:

    redis-cli --cluster create 127.0.0.1:6379 127.0.0.1:6380 127.0.0.1:6381

    This will prompt you to confirm the operation since it will permanently change the nodes' configuration. By default, this command assumes that each node has a single replica, but since you want no replicas, add the flag --cluster-replicas 0. So, the command becomes:

    redis-cli --cluster create 127.0.0.1:6379 127.0.0.1:6380 127.0.0.1:6381 --cluster-replicas 0

Please note that running a Redis cluster without replicas can be risky, as it leaves the system vulnerable to data loss in case of any node failures. Replicas are a fundamental part of high availability and resilience in a distributed system like a Redis Cluster.

Was this content helpful?

White Paper

Free System Design on AWS E-Book

Download this early release of O'Reilly's latest cloud infrastructure e-book: System Design on AWS.

Free System Design on AWS E-Book
Start building today

Dragonfly is fully compatible with the Redis ecosystem and requires no code changes to implement.