Elastic Container Instance (ECI) Pods are stateless by default — if a Pod restarts or stops, all in-container data is lost. To persist data beyond the lifetime of a Pod, mount an external storage volume. ECI supports three Alibaba Cloud storage services: cloud disks, File Storage NAS (NAS), and OSS buckets.
Alibaba Cloud provides CSI Plugin and CSI-Provisioner components based on Kubernetes community specifications. These components let self-managed Kubernetes clusters use Alibaba Cloud storage services.
Storage options
The following table compares the three storage types to help you choose the right one for your workload.
| Storage type | Cloud disk | NAS | OSS |
|---|---|---|---|
| Latency | Ultra-low (microseconds) | Low (milliseconds) | Low (tens of milliseconds) |
| Throughput | Tens of Gbit/s | Hundreds of Gbit/s | Hundreds of Gbit/s |
| Access mode | Single client — random read/write via Portable Operating System Interface of UNIX (POSIX) | Thousands of clients concurrently — random read/write via POSIX | Millions of clients concurrently — append operations via the web |
| Mounting | Not shared. A disk can be mounted to a single Pod only. | Shared. A NAS file system can be mounted to multiple Pods. | Shared. An OSS bucket can be mounted to multiple Pods. |
For detailed guidance on choosing a storage service, see Alibaba Cloud storage service selection.
Cloud disks
Cloud disks are block-level Elastic Block Storage (EBS) devices backed by a distributed multi-replica mechanism that delivers ultra-low latency, high performance, high durability, and high reliability. A disk can be created, released, and resized based on workload requirements.
For more information, see Disks.
NAS
NAS is a distributed file system that supports the Network File System (NFS) and Server Message Block (SMB) protocols, and provides shared access, elastic scalability, high reliability, and high performance.
For more information, see What is NAS?
OSS
Object Storage Service (OSS) is a secure, cost-effective, and highly reliable storage service for large volumes of unstructured data such as images and audio and video files.
For more information, see What is OSS?
Limitations
A cloud disk can be mounted to a single Pod only and cannot be shared across Pods.
OSS supports append operations via the web and is not optimized for low-latency random read/write.
What's next
Mount a storage volume to your ECI Pod: