Edit

Enable multi-zone storage redundancy in Azure Container Storage Preview

  • Article

You can improve stateful application availability by using multi-zone storage pools and zone-redundant storage (ZRS) disks when using Azure Container Storage in a multi-zone Azure Kubernetes Service (AKS) cluster. To create an AKS cluster that uses availability zones, see Use availability zones in Azure Kubernetes Service.

Prerequisites

  • This article requires version 2.0.64 or later of the Azure CLI. See How to install the Azure CLI. If you're using Azure Cloud Shell, the latest version is already installed. If you plan to run the commands locally instead of in Azure Cloud Shell, be sure to run them with administrative privileges.
  • You'll need an AKS cluster with a node pool of at least three virtual machines (VMs) for the cluster nodes, each with a minimum of four virtual CPUs (vCPUs).
  • This article assumes you've already installed Azure Container Storage on your AKS cluster.
  • You'll need the Kubernetes command-line client, kubectl. It's already installed if you're using Azure Cloud Shell, or you can install it locally by running the az aks install-cli command.

Create a multi-zone storage pool

In your storage pool definition, you can specify the zones where you want your storage capacity to be distributed across. The total storage pool capacity will be distributed evenly across the number of zones specified. For example, if two zones are specified, each zone gets half of the storage pool capacity; if three zones are specified, each zone gets one-third of the total capacity. Corresponding storage will be provisioned in each of the zones. This is useful when running workloads that offer application-level replication such as Cassandra.

If there are no nodes available in a specified zone, the capacity will be provisioned once a node is available in that zone. Persistent volumes (PVs) can only be created from storage pool capacity from one zone.

Valid values for zones are:

  • [""]
  • ["1"]
  • ["2"]
  • ["3"]
  • ["1", "2"]
  • ["1", "3"]
  • ["2", "3"]
  • ["1", "2", "3"]

Follow these steps to create a multi-zone storage pool that uses Azure Disks. For zones, choose a valid value.

  1. Use your favorite text editor to create a YAML manifest file such as code acstor-multizone-storagepool.yaml.

  2. Paste in the following code and save the file. The storage pool name value can be whatever you want. For storage, specify the amount of storage capacity for the pool in Gi or Ti.

    apiVersion: containerstorage.azure.com/v1beta1
kind: StoragePool
metadata:
  name: azuredisk
  namespace: acstor
spec:
  zones: ["1", "2", "3"]
  poolType:
    azureDisk: {}
  resources:
    requests:
      storage: 1Ti

  3. Apply the YAML manifest file to create the multi-zone storage pool.

    kubectl apply -f acstor-multizone-storagepool.yaml

Use zone-redundant storage (ZRS) disks

If your workload requires storage redundancy, you can leverage disks that use zone-redundant storage, which copies your data synchronously across three Azure availability zones in the primary region.

You can specify the disk skuName as either StandardSSD_ZRS or Premium_ZRS in your storage pool definition, as in the following example.

apiVersion: containerstorage.azure.com/v1beta1
kind: StoragePool
metadata:
  name: azuredisk
  namespace: acstor
spec:
  poolType:
    azureDisk:
      skuName: Premium_ZRS
  resources:
    requests:
      storage: 1Ti

See also