Storage classes and PV size for AKS clusters
Astra Control Service supports Azure NetApp Files, Azure managed disks, or NetApp Cloud Volumes ONTAP as the storage backend for Azure Kubernetes Service (AKS) clusters.
Azure NetApp Files
Astra Control Service supports Azure NetApp Files as the storage backend for Azure Kubernetes Service (AKS) clusters. You should understand how choosing a storage class and persistent volume size can help you meet your performance objectives.
Service levels and storage classes
Azure NetApp Files supports three service levels: Ultra storage, Premium storage, and Standard storage. Each of these service levels are designed for different performance needs:
- Ultra storage
Provides up to 128 MiB/s of throughput per 1 TiB.
- Premium storage
Provides up to 64 MiB/s of throughput per 1 TiB.
- Standard storage
Provides up to 16 Mib/s of throughput per 1 TiB.
These service levels are an attribute of a capacity pool. You need to set up a capacity pool for each service level that you want to use with your Kubernetes clusters. Learn how to set up capacity pools.
Astra Control Service uses these service levels as storage classes for your persistent volumes. When you add Kubernetes clusters to Astra Control Service, you're prompted to choose either Ultra, Premium, or Standard as the default storage class. The names of the storage classes are netapp-anf-perf-ultra, netapp-anf-perf-premium, and netapp-anf-perf-standard.
Persistent volume size and performance
As described above, the throughput for each service level is per 1 TiB of provisioned capacity. That means larger volumes provide better performance. So you should take both capacity and performance needs into consideration when provisioning volumes.
Minimum volume size
Astra Control Service provisions persistent volumes using a minimum volume size of 100 GiB, even if the PVC asks for a smaller volume size. For example, if the PVC in a Helm chart asks for 6 GiB, Astra Control Service automatically provisions a 100 GiB volume.
If you back up an application that resides on Azure NetApp Files storage, Astra Control Service automatically temporarily expands the capacity pool. After the backup is complete, Astra Control Service shrinks the capacity pool to its previous size. Depending on your Azure subscription, you might incur storage charges when this happens. You can see a history of capacity pool resize events in the Activity page event log.
If the capacity pool exceeds the maximum size allowed by the Azure subscription during the resize operation, the backup operation fails, and a warning is triggered from the Azure API.
Azure managed disks
Astra Control Service can use Container Storage Interface (CSI) drivers to interface with Azure Managed Disks as a storage backend. This service provides block-level storage that is managed by Azure.
NetApp Cloud Volumes ONTAP
For specific information on configuring NetApp Cloud Volumes ONTAP, including performance recommendations, visit the NetApp Cloud Volumes ONTAP documentation.