Alibaba Cloud provides components that are developed based on the CSI and FlexVolume volume plug-ins of the Kubernetes community. The components allow self-managed Kubernetes clusters to use Alibaba Cloud storage services, including disks, Apsara File Storage NAS (NAS), and Object Storage Service (OSS).
Introduction to cloud storage
Alibaba Cloud provides low-cost, high-reliability, and high-availability storage services for various storage resources, such as blocks, files, and objects. You can select suitable cloud storage services based on the storage requirements of your business load, and factors such as data volume, data access frequency, IOPS, and throughput. The following part describes the common Alibaba Cloud storage services.
Disks
Disks are block-level Elastic Block Storage (EBS) devices that use a distributed multi-replica mechanism to ensure low latency, high performance, high durability, and high reliability. You can create, release, and resize disks based on your business requirements. For more information, see Disks.
Apsara File Storage NAS
NAS is a distributed file system that supports both 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
OSS is a secure, cost-effective, and highly reliable Alibaba Cloud storage service that allows users to store large volumes of unstructured data, such as images, and audio and video data. For more information, see What is OSS?
The following table compares the three services.
Item | Disk | Apsara File Storage NAS | OSS |
|---|---|---|---|
Latency | Ultra-low latency (microseconds) | Low latency (milliseconds) | Low latency (tens of milliseconds) |
Throughput | Tens of gigabits per second | Hundreds of gigabits per second | Hundreds of gigabits per second |
Access mode | A single client performs random read and write operations on a disk by using POSIX APIs. | Thousands of clients concurrently perform random read and write operations on a NAS file system by using POSIX APIs. | Millions of clients concurrently access an OSS bucket and perform append operations by using the web. |
Mounting method | Disks cannot be shared. A disk can be mounted only to a single pod. | NAS file system can be shared. A NAS file system can be mounted to multiple pods. | OSS buckets can be shared. An OSS bucket can be mounted to multiple pods. |
For more information, see Alibaba Cloud storage service selection.
Volume plug-ins
You can install the CSI or FlexVolume plug-in based on the version of your Kubernetes cluster to use Alibaba Cloud storage services. Take note of the following items:
Kubernetes clusters later than v1.22 no longer support FlexVolume. If your cluster version is later than v1.16, we recommend that you install CSI.
You can install only FlexVolume on the clusters of v1.16 or earlier.
You cannot install FlexVolume and CSI on your self-managed Kubernetes cluster at the same time.