Use Azure Container Storage with Azure Elastic SAN (preview)

Article
08/06/2024

Azure Container Storage is a cloud-based volume management, deployment, and orchestration service built natively for containers. Azure Elastic SAN is a fully integrated solution that simplifies deploying, scaling, managing, and configuring a SAN, while also offering built-in cloud capabilities like high availability.

As a preview feature, you can configure Azure Container Storage to use Azure Elastic SAN. This article covers how to make that configuration. At the end of this article, you'll have a pod that's using Elastic SAN as its storage.

Prerequisites

If you don't have an Azure subscription, create a free account before you begin.
This article requires the latest version (2.35.0 or later) of the Azure CLI. See How to install the Azure CLI. If you're using the Bash environment in 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. For more information, see Get started with Azure Cloud Shell.
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.
If you haven't already installed Azure Container Storage, follow the instructions in Use Azure Container Storage with Azure Kubernetes Service.
Check if your target region is supported in Azure Container Storage regions.

Ensure you have either an Azure Container Storage Owner role or Azure Container Storage Contributor role on your subscription. Either of these roles grant permissions that allow Azure Container Storage to communicate with the Elastic SAN resource. To make this change, go to your subscription page on the Azure portal. Select Access control (IAM) > Add role assignment and search for either "Azure Container Storage Owner" or "Azure Container Storage Contributor" in the Job function roles tab. Select View > Assignments > Add assignment and add your account.
To use Azure Container Storage with Azure Elastic SAN (preview), your AKS cluster must have a node pool of at least three general purpose VMs such as standard_d4s_v5 for the cluster nodes, each with a minimum of four virtual CPUs (vCPUs).

Limitations

The following features aren't currently supported when you use Azure Container Storage to deploy and orchestrate an Elastic SAN.

Volume snapshots
Storage pool expansion

Regional availability

Azure Container Storage is only available for a subset of Azure regions:

(Africa) South Africa North
(Asia Pacific) Australia East
(Asia Pacific) East Asia
(Asia Pacific) Japan East
(Asia Pacific) Korea Central
(Asia Pacific) Southeast Asia
(Asia Pacific) Central India
(Europe) France Central
(Europe) Germany West Central
(Europe) North Europe
(Europe) West Europe
(Europe) UK South
(Europe) Sweden Central
(Europe) Switzerland North
(Middle East) UAE North
(North America) East US
(North America) East US 2
(North America) West US
(North America) West US 2
(North America) West US 3
(North America) Central US
(North America) North Central US
(North America) South Central US
(North America) West Central US
(North America) Canada Central
(North America) Canada East
(South America) Brazil South

Create and attach persistent volumes

Follow these steps to create and attach a persistent volume.

1. Create a storage pool

First, create a storage pool, which is a logical grouping of storage for your Kubernetes cluster, by defining it in a YAML manifest file.

If you enabled Azure Container Storage using az aks create or az aks update commands, you might already have a storage pool. Use kubectl get sp -n acstor to get the list of storage pools. If you have a storage pool already available that you want to use, you can skip this section and proceed to Display the available storage classes.

Follow these steps to create a storage pool with Azure Elastic SAN (preview).

Use your favorite text editor to create a YAML manifest file such as code acstor-storagepool.yaml.
Paste in the following code. The storage pool name value can be whatever you want. Adjust storage to reflect the storage capacity you want in Gi or Ti, and save the file. Azure Elastic SAN doesn't currently support resizing storage pools.
```
apiVersion: containerstorage.azure.com/v1
kind: StoragePool
metadata:
  name: managed
  namespace: acstor
spec:
  poolType:
    elasticSan: {}
  resources:
    requests: {"storage": 1Ti}
```
Apply the YAML manifest file to create the storage pool.
```
kubectl apply -f acstor-storagepool.yaml 
```
When storage pool creation is complete, you'll see a message like:
```
storagepool.containerstorage.azure.com/managed created
```
You can also run this command to check the status of the storage pool. Replace <storage-pool-name> with your storage pool name value. For this example, the value would be managed.
```
kubectl describe sp <storage-pool-name> -n acstor
```

When the storage pool is created, Azure Container Storage will create a storage class on your behalf using the naming convention acstor-<storage-pool-name>. It will also create an Azure Elastic SAN resource.

2. Display the available storage classes

When the storage pool is ready to use, you must select a storage class to define how storage is dynamically created when creating persistent volume claims and deploying persistent volumes.

Run kubectl get sc to display the available storage classes. You should see a storage class called acstor-<storage-pool-name>.

Important

Don't use the storage class that's marked internal. It's an internal storage class that's needed for Azure Container Storage to work.

3. Create a persistent volume claim

A persistent volume claim (PVC) is used to automatically provision storage based on a storage class. Follow these steps to create a PVC using the new storage class.

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

Paste in the following code and save the file. The PVC name value can be whatever you want.

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: managedpvc
spec:
  accessModes:
    - ReadWriteOnce
  storageClassName: acstor-managed # replace with the name of your storage class if different
  resources:
    requests:
      storage: 100Gi

Apply the YAML manifest file to create the PVC.
```
kubectl apply -f acstor-pvc.yaml
```
You should see output similar to:
```
persistentvolumeclaim/managedpvc created
```
You can verify the status of the PVC by running the following command:
```
kubectl describe pvc managedpvc
```

Once the PVC is created, it's ready for use by a pod.

4. Deploy a pod and attach a persistent volume

Create a pod using Fio (Flexible I/O Tester) for benchmarking and workload simulation, and specify a mount path for the persistent volume. For claimName, use the name value that you used when creating the persistent volume claim.

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

Paste in the following code and save the file.

kind: Pod
apiVersion: v1
metadata:
  name: fiopod
spec:
  nodeSelector:
    acstor.azure.com/io-engine: acstor
  volumes:
    - name: managedpv
      persistentVolumeClaim:
        claimName: managedpvc
  containers:
    - name: fio
      image: nixery.dev/shell/fio
      args:
        - sleep
        - "1000000"
      volumeMounts:
        - mountPath: "/volume"
          name: managedpv

Apply the YAML manifest file to deploy the pod.
```
kubectl apply -f acstor-pod.yaml
```
You should see output similar to the following:
```
pod/fiopod created
```
Check that the pod is running and that the persistent volume claim has been bound successfully to the pod:
```
kubectl describe pod fiopod
kubectl describe pvc managedpvc
```

Check fio testing to see its current status:

kubectl exec -it fiopod -- fio --name=benchtest --size=800m --filename=/volume/test --direct=1 --rw=randrw --ioengine=libaio --bs=4k --iodepth=16 --numjobs=8 --time_based --runtime=60

You've now deployed a pod that's using an Elastic SAN as its storage, and you can use it for your Kubernetes workloads.

Manage persistent volumes and storage pools

Now that you've created a persistent volume, you can detach and reattach it as needed. You can also delete a storage pool.

Detach and reattach a persistent volume

To detach a persistent volume, delete the pod that the persistent volume is attached to. Replace <pod-name> with the name of the pod, for example fiopod.

kubectl delete pods <pod-name>

To reattach a persistent volume, simply reference the persistent volume claim name in the YAML manifest file as described in Deploy a pod and attach a persistent volume.

To check which persistent volume a persistent volume claim is bound to, run kubectl get pvc <persistent-volume-claim-name>.

Delete a storage pool

If you want to delete a storage pool, run the following command. Replace <storage-pool-name> with the storage pool name.

kubectl delete sp -n acstor <storage-pool-name>

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