ACK integrates three Alibaba Cloud storage types through the Container Storage Interface (CSI) plugin: disks for exclusive block storage, File Storage NAS (NAS) for shared file access, and Object Storage Service (OSS) for large-scale unstructured data. Choose the storage type based on your workload's sharing requirements and access patterns.
Storage services
Disk
Disks are block-level Elastic Block Storage (EBS) devices built on a distributed multi-replica architecture, providing low latency, high performance, high durability, and high reliability.
Use disks for stateful workloads—such as databases—that require high IOPS and exclusive, low-latency block storage for a single pod.
Key constraint: A disk can only be mounted to a single pod. For workloads that need shared access across multiple pods, use NAS or OSS instead.
For more information, see Disks.
NAS
File Storage NAS is a distributed file system that supports the Network File System (NFS) and Server Message Block (SMB) protocols. It offers shared access, elastic scalability, high reliability, and high performance.
Use NAS for workloads that need concurrent read/write access to a shared file system from multiple pods—such as content management systems or shared configuration stores.
Key constraint: In ACK Serverless clusters, only statically provisioned volumes are supported. Dynamic provisioning is unavailable because Elastic Container Instance (ECI) does not support privileged permissions.
For more information, see What is NAS?
OSS
Object Storage Service (OSS) is a secure, cost-effective, and highly reliable object store for large volumes of unstructured data, such as images and audio/video files. An OSS bucket can be mounted as a volume and shared across multiple pods simultaneously.
Use OSS for workloads with read-heavy access patterns to large unstructured datasets—such as media processing pipelines or machine learning data ingestion—where multiple pods need concurrent access without additional infrastructure.
Key constraint: Only statically provisioned volumes are supported for OSS across all cluster types.
For more information, see What is OSS?
For a comparison of all Alibaba Cloud storage types, see Alibaba Cloud storage services.
Storage plugins
ACK supports two storage plugins: CSI and FlexVolume. FlexVolume is discontinued.
FlexVolume is not supported in ACK clusters running Kubernetes 1.20 or later. For more information, see FlexVolume overview.
The Kubernetes community recommends CSI. The CSI plugin consists of two components:
CSI-Plugin: handles mounting and unmounting volumes on nodes.
CSI-Provisioner: automatically creates disk volumes and NAS volumes on demand.
Limitations
| Storage type | Limitation | Cluster type |
|---|---|---|
| Disk | Cannot be shared. A disk can only be mounted to a single pod. | All cluster types |
| Disk | Supports both statically and dynamically provisioned volumes. | ACK and ACK Serverless |
| NAS | Only statically provisioned volumes are supported. Dynamic provisioning requires privileged permissions, which ECI does not support. | ACK Serverless |
| OSS | Only statically provisioned volumes are supported. | All cluster types |
Use Alibaba Cloud storage in ACK
The following table summarizes storage support across cluster types with links to configuration guides.
| Storage type | Sharing | ACK clusters | ACK Serverless clusters |
|---|---|---|---|
| Disk | Single pod only | Static + dynamic provisioning. See Disk volume. | Static + dynamic provisioning. See Disk volume overview. |
| NAS | Multiple pods | Static + dynamic provisioning. See NAS volume overview. | Static provisioning only. See NAS volume overview. |
| OSS | Multiple pods | Static provisioning only. See OSS volumes. | Static provisioning only. See Mount an OSS bucket as a volume. |