Replication: Redis (Cluster Mode Disabled) vs. Redis (Cluster Mode Enabled)

Scaling v. partitioning – Business needs change. You need to either provision for peak demand or scale as demand changes. Redis (cluster mode disabled) supports scaling. You can scale read capacity by adding or deleting replica nodes, or you can scale capacity by scaling up to a larger node type. Both of these operations take time. For more information, see Scaling Redis (Cluster Mode Disabled) clusters with replica nodes.

Redis (cluster mode enabled) supports partitioning your data across up to 500 node groups. You can dynamically change the number of shards as your business needs change. One advantage of partitioning is that you spread your load over a greater number of endpoints, which reduces access bottlenecks during peak demand. Additionally, you can accommodate a larger data set since the data can be spread across multiple servers. For information on scaling your partitions, see Scaling clusters in Redis (Cluster Mode Enabled).

Node size v. number of nodes – Because a Redis (cluster mode disabled) cluster has only one shard, the node type must be large enough to accommodate all the cluster's data plus necessary overhead. On the other hand, because you can partition your data across several shards when using a Redis (cluster mode enabled) cluster, the node types can be smaller, though you need more of them. For more information, see Choosing your node size.

Reads v. writes – If the primary load on your cluster is applications reading data, you can scale a Redis (cluster mode disabled) cluster by adding and deleting read replicas. However, there is a maximum of 5 read replicas. If the load on your cluster is write-heavy, you can benefit from the additional write endpoints of a Redis (cluster mode enabled) cluster with multiple shards.