Redshift clusters should have Multi-AZ deployments enabled

How to fix it

• Affects another check: Redshift.16 passes a subnet group with two Availability Zones, but Multi-AZ needs three, so a group fixed only for that check still blocks this one.
• Can break clients: A Multi-AZ cluster cannot be paused or resumed, and monitoring queries on STL, SVCS, SVL, SVV or STV views stop working because only SYS_ views are supported.

In the console

Redshift → Provisioned clusters dashboard → Clusters → the cluster → Actions → Activate Multi-AZ

Node type

RG or RA3 with at least 2 nodes; resize a DC2 or single-node cluster first

Cluster subnet group

One with subnets in 3 or more Availability Zones

Edit encryption

On, if the cluster is unencrypted; Multi-AZ requires encryption

Port

Within 5431 to 5455 or 8191 to 8215

Activate Multi-AZ

Selected from Actions once the settings above are in place

With the AWS CLI

aws redshift modify-cluster --cluster-identifier <cluster-id> --multi-az --region <region>

With Terraform

resource "aws_redshift_cluster" "this" {
  cluster_identifier = var.cluster_identifier
  node_type          = var.node_type
  multi_az           = true
}