Overview of volumes - Elastic Container Instance - Alibaba Cloud Documentation Center

You can mount volumes to elastic container instances as persistent storage. This topic describes the volumes that can be mounted to elastic container instances and how to configure the volumes.

Introduction to volumes

By default, files in containers are ephemeral and stored on temporary disks. This creates the following challenges for applications:

When a container crashes, its files are lost upon restart.
Files cannot be shared between containers running in the same elastic container instance.

To solve these problems, Elastic Container Instance uses volumes for persistent storage. The following table describes the types of volumes that Elastic Container Instance supports.

Volume type	Description	API mode	Console mode
Disks	Disks are block-level storage products provided by Alibaba Cloud. Disks feature low latency, high performance, high durability, and high reliability. For more information, see Disks. Disks are suitable for the following scenarios: High I/O and low-latency scenarios Disks feature low latency and high performance. They are suitable for scenarios that have high requirements for I/O and latency, such as scenarios in which databases and middleware are stored. Non-data sharing scenarios Disks are not shared storage and can be mounted to only one instance.	Supported	Not supported
NAS	File Storage NAS (NAS) is a distributed file system provided by Alibaba Cloud. NAS supports shared access and auto scaling. NAS features high reliability and high performance. For more information, see What is NAS? NAS is suitable for the following scenarios: Data sharing NAS is a shared storage type. You can access data on NAS from multiple instances at the same time. The data on NAS volumes is not deleted when the instance is deleted. NAS volumes can be used to share data between instances. Big data analysis NAS file systems provide high throughput and meet the requirement of shared storage access when large numbers of jobs are involved. Web applications NAS file systems can provision storage for web applications and content management systems. Log storage If you want to persistently store logs, we recommend that you use NAS volumes.	Supported	Supported
OSS	Object Storage Service (OSS) is a secure, cost-effective, and highly reliable Alibaba Cloud storage service that allows you to store large volumes of unstructured data, such as images and audio and video data. For more information, see What is OSS? OSS volumes are suitable for the following scenarios: Data sharing OSS is a shared storage type. You can access data on OSS from multiple instances at the same time. The data on OSS volumes is not deleted when the instance is deleted. OSS volumes can be used to share data between instances. Read-only configuration files of websites and applications The network performance of ossfs is not as good as those of local file systems. ossfs can support the read of small files. Read-only media files such as images and audio and video files OSS volumes are suitable for storing unstructured data. You can read images and audio and video files from OSS volumes. Note OSS volumes are mounted by using ossfs, which is implemented as a file system in user space (FUSE). Its performance is not ideal for write-intensive workloads. We recommend that you use other volumes such as NAS in scenarios that have high requirements for write speed.	Supported	Supported
EmptyDir	emptyDir volumes provide temporary storage. Data in an emptyDir volume is lost if the elastic container instance to which it is mounted is restarted. Important emptyDir volumes are temporary storage. When an elastic container instance to which an emptyDir volume is mounted is restarted, the data stored in the emptyDir volume is also cleared.	Supported	Supported
ConfigFile	The configuration file that is used to pass in configuration data of an elastic container instance.	Supported	Supported

Configuration description

To use a volume, you must first declare it and then mount it to a container.

API mode

When you call the CreateContainerGroup API operation to create an elastic container instance, you can declare the name and type of the volume by using the Volume.N.Name and Volume.N.Type parameters. Then, you need to configure additional parameters based on the value of Volume.N.Type.

Value of Volume.N.Type	Description	References
EmptyDirVolume	An emptyDir volume, which indicates a temporary directory.	Mount an emptyDir volume
ConfigFileVolume	A ConfigFile volume, which indicates a configuration file.	Mount a ConfigFile volume
NFSVolume	An NFS volume, which indicates a network file system, such as a NAS file system.	Mount a NAS volume
FlexVolume	A volume mounted by using the FlexVolume plug-in. This supports disks, NAS file systems, and OSS buckets.	Mount a disk volume Mount a NAS volume Mount an OSS bucket to an elastic container instance as a volume

Note

DiskVolume is also a valid value of Volume.N.Type, which indicates a disk volume. We do not recommend that you use the DiskVolume value. If you want to mount a disk, we recommend that you use the FlexVolume value.

After you specify a volume, you can use Container.VolumeMount-related parameters to mount the volume to a container.

Console mode

When you create an elastic container instance on the Elastic Container Instance buy page, you can specify volumes in the Container Group Configurations section and then mount the volumes to containers in the Container Configurations section.

Click Advanced Settings in the Container Group Configurations section and specify a volume.
The Elastic Container Instance console supports only the following volume type:
- Configuration item (ConfigFile)
- Temporary directories (emptyDir)
- NAS persistence (NFS)
- OSS persistence (FlexVolume)
In the Container Configurations section, click Advanced Settings next to a container to mount the volume to the container.