Storage classes and PV size for AKS clusters
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Astra uses Azure NetApp Files as the backend storage 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 uses these service levels as storage classes for your persistent volumes. When you add Kubernetes compute to Astra, 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 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 automatically provisions a 100 GiB volume.