Merge pull request #273815 from AllenWen-at-Azure/zrs-default

Update documents for using ZRS disks in built-in storage class

Author: ttorble

articles/aks/TOC.yml

@@ -564,6 +564,8 @@
           items:
               - name: Azure Disks
                 items:
+                    - name: Provision Azure Disk storage
+                      href: azure-csi-disk-storage-provision.md
                     - name: Azure Disks CSI driver
                       href: azure-disk-csi.md
                     - name: Use Azure Premium SSD v2 disks

articles/aks/availability-zones-overview.md

@@ -63,6 +63,10 @@ allowVolumeExpansion: true
 
 Kubernetes versions 1.12 and higher are aware of Azure availability zones. You can deploy a PersistentVolumeClaim object referencing an Azure Managed Disk in a multi-zone AKS cluster and [Kubernetes takes care of scheduling](https://kubernetes.io/docs/setup/best-practices/multiple-zones/#storage-access-for-zones) any pod that claims this PVC in the correct availability zone.
 
+Effective starting with Kubernetes version 1.29, when you deploy Azure Kubernetes Service (AKS) clusters across multiple availability zones, AKS now utilizes zone-redundant storage (ZRS) to create managed disks within built-in storage classes. ZRS ensures synchronous replication of your Azure managed disks across multiple Azure availability zones in your chosen region. This redundancy strategy enhances the resilience of your applications and safeguards your data against datacenter failures.
+
+However, it's important to note that zone-redundant storage (ZRS) comes at a higher cost compared to locally redundant storage (LRS). If cost optimization is a priority, you can create a new storage class with the `skuname` parameter set to LRS. You can then use the new storage class in your Persistent Volume Claim (PVC).
+
 ## Next steps
 
 * [Create an AKS cluster with availability zones](./availability-zones.md).

articles/aks/azure-csi-disk-storage-provision.md

@@ -74,6 +74,9 @@ Each AKS cluster includes four precreated storage classes, two of them configure
     * Standard SSDs backs Standard storage and delivers cost-effective storage while still delivering reliable performance.
 2. The *managed-csi-premium* storage class provisions a premium Azure Disk.
     * SSD-based high-performance, low-latency disks back Premium disks. They're ideal for VMs running production workloads. When you use the Azure Disk CSI driver on AKS, you can also use the `managed-csi` storage class, which is backed by Standard SSD locally redundant storage (LRS).
+3. Effective starting with Kubernetes version 1.29, when you deploy Azure Kubernetes Service (AKS) clusters across multiple availability zones, AKS now utilizes zone-redundant storage (ZRS) to create managed disks within built-in storage classes. 
+    * ZRS ensures synchronous replication of your Azure managed disks across multiple Azure availability zones in your chosen region. This redundancy strategy enhances the resilience of your applications and safeguards your data against datacenter failures.
+    * However, it's important to note that zone-redundant storage (ZRS) comes at a higher cost compared to locally redundant storage (LRS). If cost optimization is a priority, you can create a new storage class with the LRS SKU name parameter and use it in your Persistent Volume Claim (PVC).
 
 Reducing the size of a PVC is not supported due to the risk of data loss. You can edit an existing storage class using the `kubectl edit sc` command, or you can create your own custom storage class. For example, if you want to use a disk of size 4 TiB, you must create a storage class that defines `cachingmode: None` because [disk caching isn't supported for disks 4 TiB and larger][disk-host-cache-setting]. For more information about storage classes and creating your own storage class, see [Storage options for applications in AKS][storage-class-concepts].
 

articles/aks/azure-disk-csi.md

@@ -53,8 +53,8 @@ A storage class is used to define how a unit of storage is dynamically created w
 
 When you use the Azure Disk CSI driver on AKS, there are two more built-in `StorageClasses` that use the Azure Disk CSI storage driver. The other CSI storage classes are created with the cluster alongside the in-tree default storage classes.
 
-- `managed-csi`: Uses Azure Standard SSD locally redundant storage (LRS) to create a managed disk.
-- `managed-csi-premium`: Uses Azure Premium LRS to create a managed disk.
+- `managed-csi`: Uses Azure Standard SSD locally redundant storage (LRS) to create a managed disk. Effective starting with Kubernetes version 1.29, in Azure Kubernetes Service (AKS) clusters deployed across multiple availability zones, this storage class utilizes Azure Standard SSD zone-redundant storage (ZRS) to create managed disks.
+- `managed-csi-premium`: Uses Azure Premium LRS to create a managed disk. Effective starting with Kubernetes version 1.29, in Azure Kubernetes Service (AKS) clusters deployed across multiple availability zones, this storage class utilizes Azure Premium zone-redundant storage (ZRS) to create managed disks.
 
 The reclaim policy in both storage classes ensures that the underlying Azure Disks are deleted when the respective PV is deleted. The storage classes also configure the PVs to be expandable. You just need to edit the persistent volume claim (PVC) with the new size.
 

articles/aks/concepts-storage.md

@@ -160,8 +160,8 @@ For clusters using the [Container Storage Interface (CSI) drivers][csi-storage-d
 
 | Storage class | Description |
 |---|---|
-| `managed-csi` | Uses Azure Standard SSD locally redundant storage (LRS) to create a managed disk. The reclaim policy ensures that the underlying Azure Disk is deleted when the persistent volume that used it is deleted. The storage class also configures the persistent volumes to be expandable. You can edit the persistent volume claim to specify the new size. |
-| `managed-csi-premium` | Uses Azure Premium locally redundant storage (LRS) to create a managed disk. The reclaim policy again ensures that the underlying Azure Disk is deleted when the persistent volume that used it is deleted. Similarly, this storage class allows for persistent volumes to be expanded. |
+| `managed-csi` | Uses Azure Standard SSD locally redundant storage (LRS) to create a managed disk. The reclaim policy ensures that the underlying Azure Disk is deleted when the persistent volume that used it is deleted. The storage class also configures the persistent volumes to be expandable. You can edit the persistent volume claim to specify the new size. Effective starting with Kubernetes version 1.29, in Azure Kubernetes Service (AKS) clusters deployed across multiple availability zones, this storage class utilizes Azure Standard SSD zone-redundant storage (ZRS) to create managed disks.|
+| `managed-csi-premium` | Uses Azure Premium locally redundant storage (LRS) to create a managed disk. The reclaim policy again ensures that the underlying Azure Disk is deleted when the persistent volume that used it is deleted. Similarly, this storage class allows for persistent volumes to be expanded. Effective starting with Kubernetes version 1.29, in Azure Kubernetes Service (AKS) clusters deployed across multiple availability zones, this storage class utilizes Azure Premium zone-redundant storage (ZRS) to create managed disks. |
 | `azurefile-csi` | Uses Azure Standard storage to create an Azure file share. The reclaim policy ensures that the underlying Azure file share is deleted when the persistent volume that used it is deleted. |
 | `azurefile-csi-premium` | Uses Azure Premium storage to create an Azure file share. The reclaim policy ensures that the underlying Azure file share is deleted when the persistent volume that used it is deleted.|
 | `azureblob-nfs-premium` | Uses Azure Premium storage to create an Azure Blob storage container and connect using the NFS v3 protocol. The reclaim policy ensures that the underlying Azure Blob storage container is deleted when the persistent volume that used it is deleted. |
@@ -173,6 +173,10 @@ Unless you specify a storage class for a persistent volume, the default storage
 > Starting with Kubernetes version 1.21, AKS only uses CSI drivers by default and CSI migration is enabled. While existing in-tree persistent volumes continue to function, starting with version 1.26, AKS will no longer support volumes created using in-tree driver and storage provisioned for files and disk.
 >
 > The `default` class will be the same as `managed-csi`.
+>
+> Effective starting with Kubernetes version 1.29, when you deploy Azure Kubernetes Service (AKS) clusters across multiple availability zones, AKS now utilizes zone-redundant storage (ZRS) to create managed disks within built-in storage classes. ZRS ensures synchronous replication of your Azure managed disks across multiple Azure availability zones in your chosen region. This redundancy strategy enhances the resilience of your applications and safeguards your data against datacenter failures.
+
+However, it's important to note that zone-redundant storage (ZRS) comes at a higher cost compared to locally redundant storage (LRS). If cost optimization is a priority, you can create a new storage class with the `skuname` parameter set to LRS. You can then use the new storage class in your Persistent Volume Claim (PVC).
 
 You can create a storage class for other needs using `kubectl`. The following example uses premium managed disks and specifies that the underlying Azure Disk should be *retained* when you delete the pod: