Use persistent volumes in Redis Enterprise clusters

This section covers details about how persistent volumes are sized and specified for Redis Enterprise cluster deployments.

Storage types

Redis Enterprise for Kubernetes can only use storage classes supported by block storage. Block storage is mounted at the Kubernetes node level and utilizes EXT4 or XFS file systems. It can be sourced from enterprise-grade SANs or cloud environments such as EBS, Azure Managed Disks, or GCP persistent disks.

Warning:
NFS, NFS-like, and multi-read-write/shared storage options are not supported. These types of storage are often slow and can cause locking behaviors that are incompatible with the requirements of database storage.

REC persistentSpec field

To deploy a Redis Enterprise cluster with Redis Enterprise operator the spec should include a persistentSpec section, in the redis-enterprise-cluster.yaml file:

spec:
  nodes: 3
  persistentSpec:
   enabled: true
   storageClassName: "standard"
   volumeSize: "23Gi” #optional

Persistence storage is a requirement for production deployments.

Note:
For production deployments of Redis Enterprise Cluster on Kubenetes, the Redis Enterprise Cluster (REC) must be deployed with persistence enabled. The REC deployment files in the Kubernetes documentation contain this declaration by default.

Volume size

volumeSize is an optional definition. By default, if the definition is omitted, operator allocates five times (5x) the amount of memory (RAM) defined for nodes (see example below), which is the recommended persistent storage size as described in the Hardware requirements article.

To explicitly specify the persistent storage size, use the volumeSize property as described in the example above.

Warning:
Be aware the persistent volume size cannot be changed after deployment. Trying to change this value after deployment could result in unexpected and potentially damaging behavior. Please be sure your specified volumeSize is correct at the time of creation.
Note:
We recommend that you omit the volumeSize definition from the REC declaration so that the Redis Enterprise Cluster deployment on Kubenetes use the default volume size.

Storage class name

storageClassName determines the Storage Class resource, which is defined by the Kubernetes cluster administrator, to be used for persistent storage.

Different Kubernetes distributions and different deployments use different Storage Class resources.

In order to determine the Storage Class resources available for your K8s deployment, use the following command:

kubectl get StorageClass

Typically, AWS provides “gp2” as the Storage Class name while GKE uses “standard.” Azure provides two Storage Classes: "default" using HDDs, and "managed-premium" using SSDs.

Below is an example of a response to the command.
Name: gp2
IsDefaultClass: Yes
Annotations: storageclass.beta.kubernetes.io/is-default-class=true
Provisioner: kubernetes.io/aws-ebs
Parameters: encrypted=false,kmsKeyId=,type=gp2
AllowVolumeExpansion: <unset>
MountOptions: <none>
ReclaimPolicy: Delete
VolumeBindingMode: Immediate
Events: <none>
Note:
storageClassName must be specified for this deployment type.
Warning:
The storage class cannot be changed after deployment. Trying to change this value after deployment could result in unexpected and potentially damaging behavior.

Example of the redisEnterpriseNodeResources definition:

redisEnterpriseNodeResources:
  limits:
    cpu: “4000m”
    memory: 4Gi
  requests:
    cpu: “4000m”
    memory: 4Gi
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