Currently, Kubernetes clusters support two volume plug-ins: Flexvolume and CSI. This topic describes the features of these plug-ins and how to select between them based on your needs.

Differences between Flexvolume and CSI

Plug-in Feature Reference
Flexvolume Flexvolume is an old mechanism to extend Kubernetes storage systems developed by the Kubernetes community. Container Service for Kubernetes supports Flexvolume all the time. Flexvolume consists of the following three parts:
  • Flexvolume: Enables mounting and unmounting volumes. By default, Container Service for Kubernetes allows you to mount three types of volumes: disks, NAS, and OSS.
  • Disk-Controller: Enables automatic creation of disks.
  • Nas-Controller: Enables automatic creation of NAS file systems.

For more information about Flexvolume, see Overview.

For more information about upgrading Flexvolume, see Upgrade system components.

CSI CSI is a more recommended solution to expand storage in the Kubernetes community. The CSI plug-in provided by Container Service for Kubernetes is compatible with the features of its community version. CSI consists of the following two parts:
  • CSI Plug-in: Enables mounting and unmounting volumes. By default, Container Service for Kubernetes allows you to mount three types of volumes: disks, NAS, and OSS.
  • CSI Provisioner: Enables automatic creation of volumes. Currently, the provisioner supports automatic creation of disks and NAS file systems.

For more information about CSI, see Overview and alibaba-cloud-csi-driver.

Recommendations

  • For new clusters, we recommend that you use CSI. Our Container Service team will continue to upgrade CSI to support features of its community version.
  • For existing clusters, we recommend that you keep using the installed plug-in. Our Container Service team will continue to support Flexvolume as before.

Notes

  • You need to select the plug-in type when you create new clusters.
  • You cannot use both plug-ins on the same cluster.
  • You cannot convert from Flexvolume to CSI.