Does it require to put load balancer before Redis cluster

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I am using Redis Cluster on 3 Linux servers (CentOS 7). I have standard configuration i.e. 6 nodes, 3 master instances, and 3 slave instances (one master have one slave) distributed on these 3 Linux servers. I am using this setup for my web application for data caching, HTTP response caching. My aim is to read primary and write secondary i.e. Read operation should not fail or delayed.

Now I would like to ask is it necessary to configure any load balancer before by 3 Linux servers so that my web application requests to Redis cluster instances can be distributed properly on these Redis servers? Or Redis cluster itself able to handle the load distribution?

If Yes, then please mention any reference link to configure the same. I have checked official documentation Redis Cluster but it does not specify anything regarding load balancer setup.

1 Answers

If you're running Redis in "Cluster Mode" you don't need a load balancer. Your Redis client (assuming it's any good) should contact Redis for a list of which slots are on which nodes when your application starts up. It will hash keys locally (in your application) and send requests directly to the node which owns the slot for that key (which avoids the extra call to Redis which results in a MOVED response).

You should be able to configure your client to do reads on slave and writes on master - or to do both reads and writes on only masters. In addition to configuring your client, if you want to do reads on slaves, check out the READONLY command: https://redis.io/commands/readonly .

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